filter by: Publication Year
(Descending) Articles
Physica Scripta (00318949) 100(1)
In this study, a novel approach has been utilized to Please specify the corresponding author.explore the room temperature thermoelectric properties of zigzag phosphorene nanoribbon-based monolayer-bilayer-monolayer junctions. To achieve thermoelectric properties at room temperature, a quasi-flat energy band with limited width is required. It has been demonstrated, for the first time, that such bands can be observed by considering a junction of the monolayer and bilayer phosphorene nanoribbons. By adjusting the ribbon widths, quasi-flat bands are produced. This geometrical problem is solved using analytical calculations for a general system and applied to phosphorene. We show that the edge states of phosphorene resemble a one-dimensional tight-binding system, with a close agreement between their results. Using the introduced approach, we calculate the electronic energy band structure of the specified system. Initially, we demonstrate that the formation of zigzag monolayer-bilayer-monolayer junctions can lead to the emergence of quasi-flat impurity bands within the energy bandgap. Furthermore, we show that utilizing these structures at room temperature, across a wide range of lead temperature differences, results in significant output electrical power and improved thermoelectric efficiency. The electrical power and thermoelectric efficiency are examined as functions of applied bias voltage and average chemical potential. Additionally, we explore how the output electrical power, thermoelectric efficiency, and efficiency at maximum power vary with the temperature difference between the leads at the ends of the structure. © 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Iranian Journal Of Materials Science And Engineering (17350808) 22(1)pp. 37-50
Nanomaterials have significantly transformed multiple scientific and technological fields due to their exceptional properties resulting from their quantum confinement effects and high surface-to-volume ratios. Among these materials, zinc oxide (ZnO) and titanium dioxide (TiO 2) nanoparticles have attracted considerable interest because of their diverse applications. In this study, TiO2-ZnO nanocomposites were synthesized using varying calcination times of 1, 1.5, 2, 2.5, and 3 hours. Characterization of fabricated samples through X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDXS) confirmed the successful fabrication of the nanocomposites. In this regard, XRD analysis revealed anatase TiO2 and hexagonal wurtzite ZnO phases. Raman spectroscopy also supported these findings, identifying characteristic peaks of both TiO2 and ZnO. The calcination time had a minimal effect on the crystal structures and the nanocomposites' morphology, which gave rise to its negligible impact on the samples' optical properties and biological activities. Optical properties assessed using UV-visible and photoluminescence (PL) spectroscopy showed consistent band gap absorption and emission profiles across all samples, among which the nanocomposite calcined for 1 hour exhibited the best optical properties. The sample prepared at 1 hour showed the most favorable optical properties and significant antibacterial, antifungal, and cytotoxic activities, making it suitable for various applications. In this regard, more than 99.9% reduction occurred in the number of Escherichia coli, Staphylococcus aureus bacteria, and Candida albicans fungus using TiO2-ZnO nanocomposite. Besides, adding 500 µg/ml of nanocomposite decreased the cell viability to 34.47%, which signifies its high cytotoxicity activity. © 2025, Iran University of Science and Technology. All rights reserved.
Chemical Methodologies (26457776) 9(3)pp. 233-250
Nanomaterials have significantly transformed multiple scientific and technological fields due to their exceptional properties, which result from their quantum confinement effects and high surface-to-volume ratios. Among these materials, zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles have attracted considerable interest because of their diverse applications. In this study, TiO2-ZnO nanocomposites were synthesized using varying calcination times of 1, 1.5, 2, 2.5, and 3 hours. Characterization of fabricated samples through X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDXS) confirmed the successful fabrication of the nanocomposites. In this regard, XRD analysis revealed anatase TiO2 and hexagonal wurtzite ZnO phases. Raman spectroscopy also supported these findings, identifying characteristic peaks of both TiO2 and ZnO. The calcination time had a minimal effect on the crystal structures and also morphology of the nanocomposites, which gave rise to its negligible impact on optical properties and biological activities of the samples. Optical properties assessed by means of UV-visible and photoluminescence (PL) spectroscopy showed consistent band gap absorption and emission profiles across all samples, among which the nanocomposite calcined for 1 hour exhibited the best optical properties. The sample prepared at 1 hour not only showed the most favorable optical properties, but also demonstrated significant antibacterial, antifungal, and cytotoxic activities, which make it suitable for various applications. In this regard, a reduction of more than 99.9% occurred in the number of Escherichia coli and Staphylococcus aureus bacteria and also Candida albicans fungus by using TiO2-ZnO nanocomposite. Besides, addition of 500 µg/mL of nanocomposite decreased the cell viability to 34.47%, which signifies its high cytotoxicity activity. © 2025, Sami Publishing Company. All rights reserved.
Solid State Communications (00381098) 401
In this study, the Haldane model's edge states are utilized to illustrate that a zero-energy localized state forms around a single vacancy in the model. In order to complete this task, the conventional unit cell associated to the Haldane hexagonal structure is transferred onto a two-leg ladder in momentum space, effectively forming an extended Su–Schrieffer–Heeger (SSH) lattice through a one-dimensional Fourier transform. Through the application of a suitable unitary transformation, the two-leg SSH ladder in momentum space is converted into an equivalent lattice with two distinct on-site states with different momentum that are suitable for the calculations. Ultimately, the desired zero-energy localized mode formed around the vacant-site is represented by a combination of the armchair edge states. Furthermore, the scenario involving two vacant sites is investigated and it is revealed that an effective hopping interaction exists between the localized states formed around the on-site vacancies created along a zigzag chain in the lattice. This structure can be likened to the structure of a quantum dot with two none-degenerate energy levels. Such a hopping interaction is absent for the same vacancies created on the armchair chains. Finally, it is shown that introducing vacancies periodically on the sites of a zigzag row along a finite-width ribbon with the Haldane structure leads to the emergence of an impurity band within the energy gap. © 2025
Physica Scripta (00318949) 99(9)
The concept of topological Fano resonance, characterized by an ultrasharp asymmetric line shape, is a promising candidate for robust sensing applications due to its sensitivity to external parameters and immunity to structural disorder. In this study, the vacancy-induced topological Fano resonance in a nanoribbon made up of a hexagonal lattice with armchair sides is examined by introducing several on-site vacancies, which are deliberately created at regular distances, along a zigzag chain that stretches across the width of the ribbon. The presence of the on-site vacancies can create localized energy states within the electronic band structure, leading to the formation of an impurity band, which can result in Fano resonance phenomena by forming a conductivity channel between the edge modes on both armchair sides of the ribbon. Consequently, an ultracompact tunable on-chip integrated topological Fano resonance derived from the graphene-based nanomechanical phononic crystals is proposed. The Fano resonance arises from the interference between topologically protected even and odd edge modes at the interface between trivial and nontrivial insulators in a nanoribbon structure governed by the Kane-Mele model describing the quantum spin Hall effect in hexagonal lattices. The simulation of the topological Fano resonance is performed analytically using the Lippmann-Schwinger scattering formulation. One of the advantages of the present study is that the related calculations are carried out analytically, and in addition to the simplicity and directness, it reproduces the results obtained from the Landauer-Büttiker formulation very well both quantitatively and qualitatively. The findings open up possibilities for the design of highly sensitive and accurate robust sensors for detecting extremely tiny forces, masses, and spatial positions. © 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Quantum Information Processing (15700755) 23(5)
A novel method has been devised to compute the local integrals of motion (LIOMs) for a one-dimensional many-body localized system. In this approach, a class of optimal unitary transformations is deduced in a tensor network formalism to diagonalize the Hamiltonian of the specified system. To construct the tensor network, we utilize the eigenstates of the subsystems’ Hamiltonian to attain the desired unitary transformations. Subsequently, we optimize the eigenstates and acquire appropriate unitary localized operators that will represent the LIOMs tensor network. The efficiency of the method was assessed and found to be both fast and almost accurate. In framework of the introduced tensor network representation, we examine how the entanglement spreads along the considered many-body localized system and evaluate the outcomes of the approximations employed in this approach. The important and interesting result is that in the proposed tensor network approximation, if the length of the blocks is greater than the length of localization, then the entropy growth will be linear in terms of the logarithmic time. Also, it has been demonstrated that the entanglement can be calculated by only considering two blocks next to each other, if the Hamiltonian has been diagonalized using the unitary transformation made by the provided tensor network representation. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
Al-marzoog, R. ,
Rezaei, A. ,
Noorinejad z., Z. ,
Amini, M. ,
Ghanbari, E. ,
Jafari, S.A. Physical Review B (24699950) 110(16)
This study is devoted to the profound implications of tilted Dirac cones on the quantum transport properties of two-dimensional (2D) Dirac materials. These materials, characterized by their linear conic energy dispersions in the vicinity of Dirac points, exhibit unique electronic behaviors, including the emulation of massless Dirac fermions and the manifestation of relativistic phenomena such as Klein tunneling. Expanding beyond the well-studied case of graphene, the manuscript focuses on materials with tilted Dirac cones, where the anisotropic and tilted nature of the cones introduces additional richness to their electronic properties that arises from an emergent underlying spacetime geometry. The investigation begins by considering a heterojunction of 2D Dirac materials, where electrons undergo quantum tunneling between regions with upright and tilted Dirac cones. The role of tilt in characterizing the transmission of electrons across these interfaces is thoroughly examined, shedding light on the influence of the tilt parameter on the transmission probability and the fate of the pseudospin of the Dirac electrons, particularly upon a sudden change in the tilting. We also investigate the probability of reflection and transmission from an intermediate slab with arbitrary subcritical tilt, focusing on the behavior of electron transmission across regions with varying Dirac cone tilts. The study demonstrates that for certain thicknesses of the middle slab, the transmission probability is equal to unity, and both reflection and transmission exhibit periodic behavior with respect to the slab thickness. This is reminiscent of Klein tunneling across scalar potential barriers in PNP junctions, no gate voltage is applied. Such a tilt-induced potential can be considered as the quantum transport manifestation of the "gravitomagnetic"effect of underlying spacetime structure. © 2024 American Physical Society.
Quantum Information Processing (15700755) 22(1)
In the present work, the scattering of the edge-state electrons from two similar two-level atoms located as impurities near the two sites on the zigzag edge of a phosphorene ribbon has been studied theoretically with a focus on the production of entanglement between the impurities. To this end, it is assumed that the electrons are traveling parallel to the zigzag edge of a phosphorene ribbon and the edge states have been used to describe the state of these mobile electrons. Also, it is presumed that the incident electrons interact with the electric dipole of the scatterer atoms. Then, the general scattering theory based on the Lippmann–Schwinger equation has been applied along with the Green function approach to calculate the transition matrix elements and consequently the transmission and reflection probabilities of the mobile electrons. It has been shown that the problem can be reduced to the scattering of electrons along a one-dimensional chain lying along the zigzag edge of the ribbon. We then show that the scattering process leads to creation of a quantum correlation between the similar atomic impurities. Concurrence has been calculated as a measure of the produced entanglement, and its dependence on the energy of the electrons as well as the interaction strengths has been investigated and discussed. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Journal of Physics A: Mathematical and Theoretical (17518113) 56(15)
The emergent integrability in a many-body localized (MBL) system can be well characterized by the existence of the complete set of local integrals of motion (LIOMs). Such exactly conserved and exponentially localized operators are often understood as quasiparticle operators which can be expanded in terms of single-particle operators dressed with different numbers of particle-hole pairs. Here, we consider a one-dimensional XXZ spin- 1 2 Heisenberg chain in the presence of a random field and try to quantify the corrections needed to be considered in the picture of quasiparticles associated with LIOMs due to the presence of particle-hole excitations. To this end, we explicitly present the multibody expansion of LIOM creation operators of the system in the MBL regime. We analytically obtain the coefficients of this expansion and discuss the effect of higher-order corrections associated with different numbers of particle-hole excitations. Our analysis shows that depending on the localization length of the system, there exist a regime in which the contributions that come from higher-order terms can break down the effective one-particle description of the LIOMs and such quasiparticles become essentially many-body-like. © 2023 IOP Publishing Ltd.
Solid State Communications (00381098) 345
In this study, the general scattering theory based on the Lippmann–Schwinger equation, along with the Green function approach, is applied to investigate the scattering of the mobile electrons from a two-level atom located in a one-dimensional (1D) lattice. We have shown that there is a high similarity between this issue and the scattering of the edge-state electrons from a two-state atom located near the edge of a zigzag nanoribbon of phosphorene. The method is then generalized to the study of this latter case. In both cases, it is assumed that the electron interacts with the electric dipole of the atom and it is shown that the scattering process may lead to the excitation of the atom and change its initial state. For both cases, the elements of the transition matrix, the transmission and reflection coefficients, and the excitation probability of the scattering atom are analytically calculated and discussed. © 2022 Elsevier Ltd
European Physical Journal D (14346060) 76(6)
Abstract: The first-order Coulomb–Born approximation with the correct boundary conditions is used to investigate the recoil-ion momentum distribution of single-electron capture in fast collision of the fully stripped ions with the ground-state helium-like atoms. To this end, both the frozen core three-body (3B) and the active electron four-body (4B) versions of the theory are developed to calculate the post and prior transition amplitudes. The calculations are performed for the energetic collision of fully stripped boron ions with helium atoms as an example, and the obtained results are compared to the experimental data as well as the results of the other theories. The comparison shows that the 3B theory provides a reasonable description of the recoil-ion momentum distribution in shape but not in magnitude. However, there is a considerable difference between the results obtained from the prior and post forms of this formulation. Also, although the 4B model is closer to the reality of the problem, its results deviate significantly from the measurements, both in magnitude and shape. Graphic abstract: [Figure not available: see fulltext.] © 2022, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.
Europhysics Letters (02955075) 125(6)
Transport of the edge-state electrons along zigzag phosphorene nanoribbons in the presence of two impurities/vacancies is analytically investigated. Considering the places of the defects, a number of different situations are examined. When both defects are placed on the edge zigzag chain, as is expected, by changing the energy of the traveling electrons the electrical conductance exhibits a resonance behavior. In this case, for two vacancies the observed resonant peaks become extremely sharp. An amazing behavior is seen when the second vacancy is located along an armchair chain while the first is placed at the intersection of the edge zigzag and this armchair chain. In this case, in a considerable range of energy, the conductance is strongly strengthened. In fact the presence of the second vacancy creates a shielded region around the first vacancy, consequently, the traveling wave bypasses this region and enhances the conductance. The analytical results are compared with numerical simulations showing very good agreement. © 2019 EPLA.
Quantum Information Processing (15700755) 18(3)
In this paper, we investigate how two on-site doped impurities with net magnetic moments in an edge chain of a zigzag phosphorene nanoribbon (zPNR) can be entangled by scattering of the traveling edge-state electrons. To this end, in the first step, we employ the Lippmann–Schwinger equation as well as the Green’s function approach to study the scattering of the free traveling electrons from two magnetic impurities in a one-dimensional tight-binding chain. Then, following the same formalism, that is shown that the behavior of two on-site spin impurities in the edge chain of a zPNR in responding to the scattering of the edge-state traveling electrons is very similar to what happens for the one-dimensional chain. In both cases, considering a known incoming wave state, the reflected and transmitted parts of the final wave state are evaluated analytically. Using the obtained results, the related partial density matrices and the reflection and transmission probabilities are computable. Negativity as a measure of the produced entanglement in the final state is calculated, and the results are discussed. Our theoretical model actually proposes a method, which is perhaps experimentally performable to create the entanglement in the state of the impurities. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
Journal of Physics B: Atomic, Molecular and Optical Physics (09534075) 51(18)
Within the framework of an independent particle model, the differential single charge transfer process in the collision of fast helium ions with neutral helium targets is theoretically studied by means of the classical trajectory Monte Carlo (CTMC) method. Also, the specified reactions are investigated using two semiclassical continuum distorted wave models with eikonal initial and final states. These theories are usually identified as CDW-EIS and CDW-EFS. Using the CTMC theory, both the electron capture and the excitation probabilities are estimated and discussed as functions of the collision impact parameter. Also, the distribution of the final projectile (n, l) states and the impact parameter dependence of the electron transfer to the final n levels are investigated. Using the theories, the projectile angular distribution of the fully differential cross-sections are calculated for several impact energies in the range of 60-630 keV/u for which the experimental data are available. The obtained results are compared to each other and to their corresponding experimental values. In most of the considered cases, comparisons show that the applied treatments are in qualitative agreement with the experimental data. © 2018 IOP Publishing Ltd.
European Physical Journal D (14346060) 72(6)
Abstract: Three-body classical trajectory Monte Carlo method is employed to simulate the differential single electron capture process in fast proton-helium collisions. For the considered collisional system, by means of an independent particle model, both electron capture and electron excitation probabilities are evaluated in terms of the classical impact parameter and the related discussions are presented. The method is also applied to calculate the projectile-angular distribution of the cross sections in energy range of 50–630 keV. The obtained results are compared to the available precise data due to the cold-target recoil ion momentum spectroscopy and good overall agreement found with these experimental data. Also, within a classical-trajectory framework, the correlation between the impact parameter and the projectile scattering angle is examined through the simulation of the collision process. Graphical abstract: [Figure not available: see fulltext.]. © 2018, EDP Sciences, SIF, Springer-Verlag GmbH Germany, part of Springer Nature.
Journal of Physics B: Atomic, Molecular and Optical Physics (09534075) 51(9)
A semiclassical impact parameter version of the continuum distorted wave-Eikonal initial state theory is developed to study the differential ionization of Li atoms in collisions with Li2+ ions. Both post and prior forms of the transition amplitude are considered. The fully differential cross sections are calculated for the lithium targets in their ground and their first excited states and for the projectile ions at 16 MeV impact energy. The role of the inter-nuclear interaction as well as the significance of the post-prior discrepancy in the ejected electron spectra are investigated. The obtained results for ejection of the electron into the azimuthal plane are compared with the recent measurements and with their corresponding values obtained using a fully quantum mechanical version of the theory. In most of the cases, the consistency of the present approach with the experimental and the quantum theoretical data is reasonable. However, for 2p-state ionization, in the cases where no experimental data exist, there is a considerable difference between the two theoretical approaches. This difference is questionable and further experiments are needed to judge which theory makes a more accurate description of the collision dynamics. © 2018 IOP Publishing Ltd.
Ghanbari, E. ,
Fischer, D. ,
Ferreira, N. ,
Goullon, J. ,
Hubele, R. ,
Laforge, A. ,
Schulz, M. ,
Madison, D. Journal of Physics B: Atomic, Molecular and Optical Physics (09534075) 50(21)
This paper presents experimental measurements of the fully differential cross section for 16 MeV Li2+ single ionization of ground and the excited state of Li in the azimuthal plane. Data were obtained for three different ejected electron energies and two different projectile momentum transfers. The experimental results are compared with theoretical three-body continuum distorted wave-Eikonal initial state calculations and reasonable good agreement is found between theory and experiment. Theory predicts a double peak structure for one of the measured cases and the physical effects producing the double peak are investigated by performing calculations with different interactions either turned on or off. © 2017 IOP Publishing Ltd.
Europhysics Letters (02955075) 120(6)
A full quantum mechanical version of the three-body distorted wave-eikonal initial state (3DW-EIS) theory is developed to study of the single ionization of the atomic targets by ion impact at different momentum transfers. The calculations are performed both with and without including the internuclear interaction in the transition amplitude. For 16 Mev O7+-He (1s2) and 24Mev O8+-Li (2s) collisions, the emission of the active electron into the scattering plane is considered and the fully differential cross-sections (FDCSs) are calculated for a fixed value of the ejected electron energy and a variety of momentum transfers. For both the specified collision systems, the obtained results are compared with the experimental data and with the crosssections obtained using the semi-classical continuum distorted wave-eikonal initial state (CDWEIS) approach. For 16Mev O7+-He (1s2), we also compared the results with those of a four-body three-Coulomb-wave (3CW) model. In general, we find some large discrepancies between the results obtained by different theories. These discrepancies are much more significant at larger momentum transfers. Also, for some ranges of the electron emission angles the results are much more sensitive to the internuclear interaction to be either turned on or off. © EPLA, 2018.
Ghanbari, E. ,
Fischer, D. ,
Ferreira, N. ,
Goullon, J. ,
Hubele, R. ,
Laforge, A. ,
Schulz, M. ,
Madison, D. Physical Review A (24699934) 94(2)
This paper presents a full three-dimensional (3D) comparison between experiment and theory for 24 MeV O8+ single ionization of the 2s ground state of lithium and the 2p excited state. Two theoretical approximations are examined: the three-body continuum distorted-wave (3DW) and three-body continuum distorted-wave-eikonal initial state (3DW-EIS). Normally, there is a significant difference between these two approaches and the 3DW-EIS is in much better agreement with experiment. In this case, there is very little difference between the two approaches and both are in very good agreement with experiment. For the excited 2p state, the 3D cross sections would exhibit a mirror symmetry about the scattering plane if all three magnetic sublevels were excited in equal proportions. For the present experiment, the 2p+1(m=+1) sublevel is dominantly excited (quantization axis is the incident beam direction) and for this case there is a magnetic dichroism which is observed both experimentally and theoretically. © 2016 American Physical Society.
Quantum Information Processing (15700755) 15(6)pp. 2377-2391
Scattering of a ballistic electron by the quantum-dot spin qubits fixed in a graphene nanoribbon is investigated theoretically. Two simple cases are investigated in details: scattering from a static quantum dot and scattering from two static quantum dots located at a fixed distance from each other. For the first case, it is shown that the Klein tunneling in a graphene sheet leads to a final entangled state for the reflected and/or transmitted electrons. The amount of the generated entanglement through the scattering process is a function of the incident angle for the ballistic electrons. For the second case, it is shown that the created correlation between the quantum dots is a periodic function of their distance. For frontal incident electrons in both cases, there is not any reflection and the Klein tunneling effect leads to a final well-correlated state for the scattering system. © 2016, Springer Science+Business Media New York.
Europhysics Letters (02955075) 116(6)
Molecular three-body Brauner-Briggs-Klar (M3BBK) theory is developed to study the single ionization of diatomic molecules by ion impact. The orientation-averaged molecular orbital (OAMO) approximation is used to reduce the required computer time without sacrificing the performance of the method. The post-collision interaction (PCI) between the scattered projectile and the ejected electron is included. The theory is applied to collision of protons with hydrogen molecules. Results are obtained for two different kinematical regimes: i) fast collisions and low emission energies, and ii) not so fast collisions and higher emission energies. For both considered regimes, experimental fully differential cross-sections as well as different theoretical calculations are available for comparison. These comparisons are carried out and discussed. © CopyrightEPLA, 2016.
Quantum Information Processing (15700755) 15(10)pp. 4219-4236
Entanglement generation due to low-energy scattering of the transporting electrons in an electronic waveguide by a quantum dot magnetic impurity is theoretically investigated. The transverse confining potential of the waveguide is considered as a two-dimensional harmonic potential, and the interaction of the electron with the impurity is described by a zero-range pseudopotential modulated by an Ising or a Heisenberg spin interaction. Our calculation shows that the scattering process leads to creation of a considerable amount of entanglement in the state of the reflected and transmitted electrons. The situation is extended to the scattering of the electrons by two well-separated magnetic impurities localized on the nanowire axis. It is shown that the scattering process causes the magnetic impurities embedded in the nanowire to share their quantum information; subsequently, they can be entangled by spin interaction with the injected electron. The created entanglement between the impurities is calculated and discussed. It is shown that the exact three-dimensional problem can be approximated as a one-dimensional problem under certain circumstances. The approximate results are compared to exact calculations and discussed. © 2016, Springer Science+Business Media New York.
Molecular Physics (00268976) 113(21)pp. 3336-3344
A four-body eikonal approximation is developed to study the single-electron capture process in collision of the fast protons with the hydrogen molecular targets. For a fixed orientation of the molecular axis, the double-differential cross sections are evaluated for electron capture. Interference patterns originated from the two atomic centres are obtained for different orientations of the molecular target. Equal-weighted average of the differential capture cross sections over all the possible orientations of the molecular target is calculated for various impact energies. Angular distributions of the differential cross sections for single charge transfer at various impact energies as a function of the angle between the axis of the molecule and the incident beam direction are calculated and compared with their corresponding experimental values as well as the results obtained from other theories. Integrated cross sections are calculated and compared with available experimental data and other theoretical calculations. © 2015 Taylor & Francis.
Chinese Physics B (16741056) 24(1)
A four-body distorted-wave approximation is applied for theoretical analysis of the fully differential cross sections (FDCS) for proton-impact single ionization of helium atoms in their ground states. The nine-dimensional integrals for the partial amplitudes are analytically reduced to closed-form expressions or some one-dimensional integrals which can be easily calculated numerically. Calculations are performed in the scattering and perpendicular planes. The influence of the target static electron correlations on the process is investigated using a number of different bound-state wave functions for the ground state of the helium targets. An illustrative computation is performed for 75-keV proton-helium collisions and the obtained results are compared with experimental data and other theoretical predictions. Although for small momentum transfers, the comparison shows a reasonable agreement with experiments in the scattering and perpendicular planes, some significant discrepancies are still present at large momentum transfers in these planes. However, our results are compatible and for some cases, better than those of the other sophisticated calculations. © 2015 Chinese Physical Society and IOP Publishing Ltd.
Journal of Physics B: Atomic, Molecular and Optical Physics (09534075) 48(19)
A two-effective-center approximation with two Coulomb wave functions is applied to calculate the fully differential cross-sections for fast proton-impact single ionization of hydrogen molecules. The approximation satisfies the correct boundary conditions in the entrance channel. For each of the effective scatterer centers, two Coulomb waves representing the propagation of the projectile and the ejected electron in the field of the residual unscreened core are included in the final continuum state for the ionized system that is considered. Only the direct partial amplitudes are calculated and the indirect partial amplitudes are included in the formalism using a normalization procedure. Overall, the predictions and the available experimental values are found to be in good agreement. © 2015 IOP Publishing Ltd.
European Physical Journal D (14346060) 69(7)
Abstract In this paper, the entanglement and quantum discord created due to a one-dimensional scattering process occurring in a system including two observers, Alice and Bob, is theoretically investigated. In this process, Alice sends a qubit to Bob who is located next to a fixed localized impurity. The impurity is considered as a qubit too. After a Kondo interaction occurred between the components, the incident particle is reflected to Alice by a definite probability. The scattering process generates a correlation between the reflected and the fixed localized particles. We consider different setups for such a scattering process and calculate both the entanglement and the quantum discord created between the ingredients. Both the plane-wave and Gaussian-wave treatments of the incident particle are examined. The dependence of the created entanglement on the initial width of the incident Gaussian wave packet is explored. It is shown that setting the impurity between the incident particle and an infinite potential wall is an effective way to produce a considerable entanglement in the final state. © 2015 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
Chinese Physics B (16741056) 24(7)
The first-order correct-boundary Coulomb-Born distorted-wave approximation is used to study the double-electron capture by protons from the ground-state helium atoms at intermediate and high impact energies. The differential double capture cross sections are obtained as a function of the projectile scattering angle and the total cross sections as a function of the impact energy. In the considered range of impact energy, our calculation shows that although the results are not so sensitive to the static inter-electronic correlations in the initial channel, the strong final-state correlations have a large effect on the magnitudes of the double capture cross sections. The calculated differential and integral cross sections are compared with their available experimental values. The comparison shows a good agreement between the present calculations and the measurements. The comparison of the integral cross sections shows that the present approach is compatible with other theories. © 2015 Chinese Physical Society and IOP Publishing Ltd.
International Journal of Modern Physics E (17936608) 24(12)
A first-order four-body perturbation theory is developed to calculate both the differential and integral cross-sections for K-shell charge exchange from multi-electron atomic targets to the 1s bound state of the fast proton projectiles. The correct boundary conditions are incorporated in the formalism. The model is applied to the single electron capture process from carbon, nitrogen, oxygen, neon and argon atoms for which the experimental data are available. The results are compared with their corresponding experimental values and also with those obtained from three-body version of the theory. A comparison is also made between the present predicted cross-sections and those obtained from other theories. Comparisons show that the suggested approximation is in reasonable agreement with the experimental data and is compatible with the other theories. © 2015 World Scientific Publishing Company.
Chinese Physics B (16741056) 24(3)
The four-body Coulomb-Born distorted wave approximation is applied to investigate the integral as well as projectile angular-differential cross sections for single-electron capture in the collision of energetic singly positive charged helium ions with helium atoms in their ground states. The formalism satisfies the correct boundary conditions. The influence of the dynamic electron correlations on the cross sections is studied by considering the inter electronic interactions in the complete perturbation potentials in post form. Also, the sensitivity of the cross sections to the static electronic correlations is studied by using the single-zeta and the highly correlated Byron-Joachain wave functions to describe the initial bound state of the active electrons. The obtained results for the energy range of 40-5000 keV/amu are reported and compared with other three- and four-body theoretical data and available experimental measurements. The comparison leads us to discuss the validity of the applied approach and survey the interaction effects on the cross sections by recognizing the electron-electron interaction. Particularly, for differential cross sections, the comparison of the present four-body method with the experiment shows that the agreement is not as good as that for its three-body version. © 2015 Chinese Physical Society and IOP Publishing Ltd.
International Journal of Modern Physics E (17936608) 24(12)
Single charge transfer process in collision of energetic protons with molecular hydrogens is theoretically studied using a first-order two-effective-center Born approximation. The correct boundary conditions are incorporated in the formalism and the Hartree-Fock molecular wave function for molecular targets and the residual ions are used to calculate the transition amplitude. The interference patterns in the capture differential cross-sections (DCSs) for a given fixed orientation of the molecule, due to the scattering from the two-atomic centers in the molecular targets, are examined. The dependence of the DCSs upon the angle between the molecular axis and the direction of the incident velocity is theoretically investigated. Both average differential and integral cross-sections are calculated. The obtained results are compared with the available experimental data. © 2015 World Scientific Publishing Company.
Chinese Physics B (16741056) 24(10)
A four-body distorted wave approximation is presented for theoretical investigations of the single ionization of ground-state helium atoms by fully stripped carbon ions at impact energies of 2 MeV/amu and 100 MeV/amu. The nine-dimensional integrals for the partial quantum-mechanical transition amplitudes of the specified reaction are reduced to some analytical expressions or one-dimensional integrals over real variables. Fully differential cross sections (FDCSs) are calculated and compared with their experimental values as well as the results obtained from other theories. Despite the simplicity and quickness of the proposed quadrature, the comparison shows that the obtained results are in reasonable agreement with the experiment and are compatible with those of other complicated theories. © 2015 Chinese Physical Society and IOP Publishing Ltd.
European Physical Journal D (14346060) 69(10)
Some closed-form expressions are derived for the partial direct and indirect transition amplitudes for proton-impact single ionization of the hydrogen molecules using a first-order two-effective center continuum-wave approximation. The method satisfies the correct boundary conditions in the entrance channel. The basic assumption in this model is that when the active electron is ionized from one of the atomic centers in the molecule, the other scattering center is completely screened by the passive electron. Consequently, the transition amplitude can be expressed as a superposition of the partial ionization amplitudes from two independent scattering centers located at a constant distance from each other. The superposition of the partial amplitudes leads to different interference patterns for various orientations of the molecular target. The calculated cross sections are compared with the experiments and also with other theories. The comparison shows that the present results are reliable. Graphical abstract: [Figure not available: see fulltext]. © 2015 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
Few-Body Systems (01777963) 55(11)pp. 1109-1123
A four-body theoretical study of the single charge transfer process in collision of energetic alpha ions with helium atoms in their ground states is presented. The model utilizes the Coulomb–Born distorted wave approximation with correct boundary conditions to calculate the single-electron capture differential and integral cross sections. The influence of the dynamic and static electron correlations on the capture probability is investigated. The results of the calculations are compared with the recent experimental measurements for differential cross sections and with the other theoretical manipulations. The results for scattering at extreme forward angles are in good agreement with the experimental measurements, but in other scattering angles the agreement is poor. However, the present four-body results for integral cross sections are in excellent agreement with the experimental data. © 2014, Springer-Verlag Wien.
International Journal of Modern Physics E (17936608) 23(12)
A four-body boundary-corrected first-order Jackson-Schiff approximation (JS1-4B) is developed to calculate the differential and integral cross-sections (DCSs) for double-electron exchange in collision of fast alpha ions with helium atoms in their ground states. The influence of the static electron correlations on cross-sections is taken into account through choosing the different wave functions to describe the initial and final bound states of the electrons. The quantum-mechanical post and prior transition amplitudes for double charge exchange are derived in terms of two-dimensional real integrals which can be calculated numerically. The validity and utility of the applied approach is critically assessed in comparison with the available experimental data for differential and integral cross-sections. The present calculations are also compared with the results obtained from the other theories. © 2014 World Scientific Publishing Company.
European Physical Journal D (14346060) 68(11)
Entanglement generation in the one-dimensional collision of two initially uncorrelated spin-1/2 particles is analyzed. It is assumed that the colliding particles interact with each other through a delta potential with a spin-spin coupling strength. Two different approaches are followed. In the first approach, the colliding particles are described by plane waves and in the second one by Gaussian wave packets. It is shown that the collision process create a final state which may be entangled in both momentum and spin spaces. The magnitude of the created entanglement is a function of the potential strength, the initial spin state and the initial momentum of the particles. By changing the initial spin state of the system, an entanglement exchange occurs between the k and spin spaces. Also, the present wave-packet analysis demonstrates, somewhat surprisingly, that initial widths of the wave packets describing the colliding particles play but a minor role for the entanglement generation process. © 2014 EDP Sciences, Società Italiana di Fisica, Springer-Verlag.
European Physical Journal D (14346060) 68(4)
Generation of quantum entanglement in scattering of particles from fixed localized spin impurities is investigated. In the suggested approach, the incident particle is described by a Gaussian wave packet with an initial definite width. It is also assumed that the incident particle interacts with the impurities through the Ising and/or Heisenberg interactions. It is shown that the created entanglement is strongly affected by the initial width of the incident wave packet. For an initially well localized wave packet the created entanglement is low. However, as the initial width increases the entanglement grows appreciably and for sufficiently large values of the initial width the present results tend to our previous results for scattering of plane waves from spin impurities. For scattering from a double spin impurity, it is shown that the periodic behavior of the previous results changes significantly. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
Central European Journal of Physics (18951082) 12(3)pp. 192-202
The four-body Coulomb-Born distorted-wave approximation with correct boundary conditions (CBDW-4B) is applied to the K-shell positronium formation from multi-electron atoms at intermediate and high impact energies. In the present approach, both K-shell electrons are treated as active electrons. For collisions of positrons with helium, carbon, and neon atoms, both the post and prior forms of the transition amplitude are calculated and the corresponding differential and integral cross sections are compared with the results of the three-body version of the formalism (CBDW-3B). In order to investigate the effects of the static electronic correlations on the process, initial bound states of the active electrons in helium atoms are described by Hylleraas and Silverman wave functions. Also for positronium formation from helium atoms the obtained cross sections are compared with the available experimental data and also with the results of the other theories. © Versita sp. z o. o.
Physica Scripta (00318949) 89(10)
Both the post and prior versions of the four-body Coulomb-Born distorted wave (CBDW-4B) approximation are applied to calculate the single-electron capture differential and integral cross sections in collision of the fast protons with helium atoms. The outlined model satisfies the correct boundary conditions, and the incident energy is considered in a range of 20 to 1000 keV for which the applied approach is valid. For proton-helium collisions, the CBDW-4B method exactly coincides with the four-body first-order Jackson-Schiff approximation (JS1-4B). The influence of the static and dynamic electronic correlations on the cross sections is investigated. The ground state of the helium atom is described using two different wave functions to show the influence of the static correlation on the captured cross sections. In order to illustrate the validity of the present method, the obtained results are compared with the other theoretical investigations as well as the available experimental measurements. Although the overall agreement of the present numerical differential cross sections (DCS) with the reported experimental findings is acceptable, contrary to our general expectation, the three-body version of the formalism gives a better description of the angular distribution of the captured cross sections. However, for integral cross sections, the agreement of the four-body results with the reported measurements is better than those of three-body formalism. © 2014 The Royal Swedish Academy of Sciences.
International Journal of Theoretical Physics (15729575) 53(12)pp. 4310-4325
The dynamic behavior of the quantum discord in one-dimensional scattering of a qubit (a spin-1/2 particle) by single and double well-localized fixed spin impurities is investigated theoretically. It is assumed that the incident particle is scattered by the spin impurities through the Ising and/or Heisenberg interactions. These potentials create quantum mechanical correlation between the reflected and transmitted parts of the scattered system and the impurities. It is shown that the incident momentum, strength of the interaction potentials, and the separation between the impurities can be regarded as the control parameters for the quantum discord and concurrence manipulations. In particular, it has been found that the correlations are periodic functions of the wavelength of the incident particle when it is scattered by the double spin impurities. © 2014, Springer Science+Business Media New York.
European Physical Journal D (14346060) 67(12)
A four-body approach based on the three-Coulomb distorted wave (3CDW) model is applied to study of the electron-impact single ionization of helium atoms. Triply differential cross sections (TDCS) are calculated for different values of the incident and ejection energies and various amounts of the scattering angles. The ejection angular distribution of the TDCS in general exhibits two peaks, binary and recoil peaks. The obtained results are compared with the available experimental data as well as other theoretical predictions. The comparison shows a good agreement between the present calculations and the measurements. Also, the obtained results are compatible with the other theories. © 2013 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
Journal of Physics B: Atomic, Molecular and Optical Physics (13616455) 46(6)
The three- and four-body boundary-corrected first Born approximations are formulated for the single-electron capture from the K shell of helium, carbon and neon atoms by impact of positrons. These approximations are applied to calculate the post and prior forms of the T-matrix elements. The differential and total cross sections obtained from these transition amplitudes are compared. In order to avoid the discrepancy between the post and prior formalisms, their average amplitude is calculated to obtain the total cross sections. For helium atoms, the total cross sections obtained from the post-, prior- and averaged-transition amplitudes calculated by the three-body approximation are compared with available experimental data as well as other theories, and also with the corresponding values obtained from a four-body formalism. In comparison with the three-body version of the specified method, the results obtained from the averaged four-body transition amplitude are in better agreement with the experiment, while the situation is the reverse for the prior calculations. © 2013 IOP Publishing Ltd.
European Physical Journal D (14346060) 67(6)
In this paper, entanglement generation by scattering of particles from spin impurities is analyzed. At first, a problem in which an incident particle interacts with an impurity through the Ising and/or Heisenberg interactions is considered. Then, the analysis is extended to investigate the entanglement creation in scattering of particles form two impurities with the same interactions. When the particle is scattered by two impurities, it is shown that a quantum correlation is created between the impurities which is periodic with respect to wavelength of the incident particle. For this case, also it is shown that the Ising interaction is more effective for creating the entanglement between the impurities than the Heisenberg interaction. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2013.
Central European Journal of Physics (16443608) 11(4)pp. 423-430
Single-electron capture from the K shell of atomic targets by impact of protons at moderate and high energies has been studied using a first-order three-body Coulomb-Born continuum distorted wave approximation. The applied formalism satisfies the correct Coulomb boundary conditions. Single-zeta Roothaan-Hartree-Fock wave functions are used to describe the initial electronic bound state of the exchanged electron. Both differential and integral capture cross sections are calculated for impact of protons on carbon, nitrogen, oxygen, neon and argon atoms. The results are compared with the available measurements and other theories. The agreement between the calculations and experimental data is remarkable. © 2013 Versita Warsaw and Springer-Verlag Wien.
Brazilian Journal of Physics (16784448) 42(3-4)pp. 172-179
The differential and total cross sections for electron capture by positrons from helium atoms are calculated using a first-order distorted wave theory satisfying the Coulomb boundary conditions. In this formalism, a parametric potential is used to describe the electron screening in a consistent and realistic manner. The present procedure is self-consistent because (a) it satisfies the correct boundary conditions and post-prior symmetry, and (b) the potential and the electron binding energies appearing in the transition amplitude are consistent with the wave functions describing the collision system. The results are compared with the other theories and with the available experimental measurements. At the considered range of collision energies, the results agree reasonably well with recent experiments and theories. © 2012 Sociedade Brasileira de Física.
Journal of Physics B: Atomic, Molecular and Optical Physics (13616455) 45(23)
A three-body Coulomb-Born continuum distorted-wave approximation is applied to calculate the differential and total cross sections for single-electron exchange in the collision of fast alpha particles with helium atoms in their ground states. The applied first-order distorted wave theory satisfies correct Coulomb boundary conditions. Both post and prior forms of the transition amplitude are calculated. The nuclear-screening effect of the passive electron on the differential and total cross sections is investigated. The results are compared with those of other theories and with the available experimental data. For differential cross sections, the comparisons show a reasonable agreement with empirical measurements at higher impact energies. The agreement between experimental data and the present calculations for total cross sections with the average of the post and prior forms of the transition amplitude is reasonable at all the specified energies. © 2012 IOP Publishing Ltd.
Journal Of Sciences Islamic Republic Of Iran (10161104) 23(4)pp. 357-365
An analytical treatment of the electron screening effect within an activeelectron model is given for positronium formation from helium atoms. A firstorder distorted wave approximation with correct boundary conditions is applied to evaluate the transition amplitude. In the range of impact energy for which the introduced perturbative approach is valid, both the total and differential cross sections are calculated and the results for total cross sections are compared with the other calculations and with the available experimental data.
European Physical Journal D (14346060) 66(12)
The first-order three-body Coulomb-Born distorted wave approximation is presented to describe single-electron capture from helium atoms in their ground states by impact of energetic singly positive charged helium ions. The applied theory satisfies the correct boundary conditions. The nuclear-screening influence of the passive electrons on the electron capture process is investigated using single-zeta wavefunctions and considering the different reasonable values for effective nuclear charges. Both differential and total cross sections are calculated and compared with the available experimental data as well as other theoretical results to specify the validity of our findings. © 2012 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
Journal of Physics B: Atomic, Molecular and Optical Physics (13616455) 44(16)
The single-electron capture process in the collision of fast protons with ground-state helium atoms is studied assuming an independent-particle model. The three-body first-order Coulomb-Born distorted wave formalism, including nuclear-electronic and internuclear interactions, with correct boundary conditions is applied to the considered rearrangement process. A single-zeta Roothaan-Hartree-Fock wave function describing helium in its ground state is used to carry out the calculations. Differential and integrated cross sections are calculated for a range of the incident energy for which the present formalism is valid. The comparison of the obtained results with the corresponding experimental measurements and other three- and four-body theoretical calculations shows reasonable agreement. © 2011 IOP Publishing Ltd.
European Physical Journal D (14346060) 62(3)pp. 389-397
The first-order Coulomb-Born approximation has been applied to the study of positronium formation through K-shell electron capture in the collision of positron with multi-electron atomic targets. The single-zeta Roothaan-Hartree-Fock wave functions are used to describe the electron initial bound states. The differential and total cross sections are computed for the impact of positron on helium, carbon, neon, sodium and argon atoms, with the formation of positronium in its ground state. For helium atoms, the calculated total cross sections are compared with the available experimental data and other theoretical calculations. The comparison shows a good agreement between the present calculations and the measurements. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2011.
Journal of Physics B: Atomic, Molecular and Optical Physics (09534075) 43(3)
Several new analytical forms for the off-the-energy-shell transition matrix are presented which, in some cases, have hypergeometric functions appearing in the expressions for them. The scale of deviation of the Coulomb T-matrix from the Coulomb potential is determined. The Coulomb T-matrix derived by Shastry et al (1970 Phys. Rev. A 1 1137) is corrected by an additional term. Further, the study derives the energy shell limit for the hypergeometric forms using the Padé approximation, in which these forms are compared to the limit of exact off-shell forms in the vicinity of the energy shell. Finally, wavelet theory and multiresolution analysis are employed to arrive at a new approximate form for the Coulomb off-shell T-matrix in the Haar scalet basis.
Journal of Physics B: Atomic, Molecular and Optical Physics (13616455) 43(13)
The differential cross sections for antihydrogen formation, in ground and excited states, from energetic antiproton-positronium collisions are computed analytically, using the Faddeev formalism in a second-order approximation. At the considered range of the impact energy, the second-order terms corresponding to the classical Thomas double-scattering processes are dominant. It is also shown that there exists a dynamical interference between two of the second-order partial amplitudes. Both amplitudes correspond to classical double-collision mechanisms in which the laboratory critical angle is 0.54 mrad. The interference between these amplitudes is approximately destructive for the capture into s-states with even parity. © 2010 IOP Publishing Ltd.
Iranian Journal of Physics Research (16826957) 10(3)pp. 209-218
In this project, the Faddeev-Watson-Lovelace (FWL) formalism is generalized to large scattering angles. The angular range includes 0-180 degrees. Using this method, the charge transfer differential cross-sections are calculated, in a second-order approximation, for collision of energetic positrons and electrons with neutral positronium atoms. In this approximation, the rearrangement amplitude contains two first-order and three second-order partial amplitudes. The first first-order term is the Born amplitude in a first-order approximation. The second one corresponds to capturing the transferred particle without perturbing the state of this particle. This term, in fact, describes a knock-on process. Since the masses of the particles and the absolute values of their charges are equal, one expects that the second-order terms be similar in magnitude. This aspect causes the instructive interference of the partial amplitudes in some angles and destructive interference in some others. However, it is predicted that these amplitudes have local maxima in direction of the recoiling of the projectile. In order to investigate this situation, the second-order partial amplitudes are calculated and their relations with the parity of the initial and final states of the scattering system are analyzed. In particular, the role of dynamical interference of these partial amplitudes in creation of the kinematical peak and the peak corresponding to the knock-on scattering in angular distribution of the differential cross sections is investigated.
Journal of Physics B: Atomic, Molecular and Optical Physics (13616455) 43(6)
The charge transfer process in the collision of fast protons with hydrogen molecules is theoretically investigated using the second-order Born approximation with correct boundary conditions. In addition to two first-order terms, the present calculations include the three second-order terms which correspond to the Thomas two-step scattering mechanisms. The interference effects, due to the scattering of the particles from two atomic centres, on the electron capture differential cross sections vary significantly with the orientation of the molecule and with the impact energy. After the averaging over all molecular orientations the interference patterns disappear but the Thomas peak becomes more pronounced. These patterns are also apparent in the differential cross sections as a function of the angle between the molecular axis and the incident beam direction. The integrated cross sections are calculated and the results are compared with available experimental data. © 2010 IOP Publishing Ltd.
Shojaei f., ,
Ghanbari, E. ,
Brunger m.j., ,
Bolorizadeh m.a., Journal of Mathematical Physics (10897658) 50(1)
We derive an exact analytic form for the second-order nuclear amplitudes, under the Faddeev three-body approach, which is applicable to the nonrelativistic high energy impact interaction where positronium is formed in the collision of a positron with an atom. © 2009 American Institute of Physics.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms (0168583X) 267(19)pp. 3319-3322
The single-electron capture process in the collision of fast alpha particles with hydrogen molecules is treated using the first-order Born approximation with correct boundary conditions. The results are obtained by considering both the inter-nuclear and nuclear-electronic interactions and by employing a Hartree-Fock molecular wave function. Double differential cross sections are evaluated for the electron capture from a molecular target with a fixed orientation. In the fixed-nuclei approximation, the differential cross sections are calculated for an equally-weighted averaging over all molecular orientations. The interference patterns, due to the scattering from two atomic centers, are apparent in different forms both in the double differential cross sections and in the cross sections as a function of the angle between the molecular axis and the incident direction. Integrated cross sections are calculated and compared with other theoretical and experimental results. © 2009 Elsevier B.V. All rights reserved.
Ghanbari, E. ,
Brunger m.j., ,
Bolorizadeh m.a., ,
Campbell l., Physical Review A - Atomic, Molecular, and Optical Physics (10502947) 75(2)
The second-order Faddeev-Watson-Lovelace approximation in a modified form is applied to charge transfer from hydrogenlike target atoms by a fully stripped energetic projectile ion. The state-to-state, nlm→ n′ l′ m′, partial transition amplitudes are calculated analytically. The method is specifically applied to the collision of protons with hydrogen atoms, where differential cross sections of different transitions are calculated for incident energies of 2.8 and 5.0 MeV. It is shown that the Thomas peak is present in all transition cross sections. The partial cross sections are then summed and compared with the available forward-angle experimental data, showing good agreement. © 2007 The American Physical Society.
Bolorizadeh m.a., ,
Brunger m.j., ,
Maddern t., ,
Ghanbari, E. Journal of Mathematical Physics (10897658) 48(3)
We derive the exact analytic form for the second-order positron-electron interaction term in the Faddeev three-body approach which is applicable in the nonrelativistic high energy region. Although there is no nonintegrable singularity in the six-dimensional integral form of this amplitude, here the basic difficulty arises from the presence of complex nonintegral exponents in the components included in the integrand. Consequently, three brunch cuts must be handled simultaneously. However, by using an integral representation of the gamma function, these brunch cuts are removed from the integrand. Expanding the radial parts of the initial and final wave functions further reduces the second-order positron-electron interaction term to a one-variable integral in terms of Bessel functions of the third kind. The different final closed expressions are ultimately derived in terms of the generalized hypergeometric functions for different regions of the scattering angle. © 2007 American Institute of Physics.
Few-Body Systems (01777963) 39(1-2)pp. 11-25
Off-the-shell anomalous factors of the two-body Coulomb transition matrices appear in the integral form of the Faddeev second-order nuclear-electronic amplitude, for proton-hydrogen charge transfer scattering in a typical nlm → n′l′m′ transition. A symmetric-impulse approximation (SIA) is applied to eliminate these factors and an induction method is proposed to analytically calculate the remaining integrals. The nuclear-electronic amplitude is derived for the general case, and for totally symmetric collisions, in terms of generalized hypergeometric functions of two variables, F 4, and of one variable, 3 F 2, respectively. The angular distribution of the second-order nuclear-electronic charge transfer amplitude shows the Thomas mechanism as a peak or a hump for symmetric and asymmetric collisions. There also exists a peak in the forward angular distribution of the second-order nuclear-electronic amplitude, which partly cancels the kinematic peak in the angular distribution of the charge transfer differential cross sections.
Journal of Physics B: Atomic, Molecular and Optical Physics (09534075) 37(16)pp. 3321-3338
The Faddeev-Watson-Lovelace (FWL) treatment, in a second-order approximation, and an active electron model have been applied to calculate the single-electron capture differential cross sections from K-, L- and M-shells of many-electron atoms by protons at medium and high (but non-relativistic) impact energies. The radial part of the wavefunction for the active electron was obtained by constructing suitable bases from merging hyperbolic cosine functions with Slater-type radial ones. Converting the Schrödinger-like equation obtained from Hartree-Fock theory gives the effective potential, which is experienced by the active electron in the target atom. A simple analytic radial function composed of a Coulomb and a Yukawa potential was fitted to the effective potential. Near-the-shell two-body T-matrices, electronic-nuclear and inter-nuclear partial amplitudes are calculated to obtain the electron capture differential cross sections between various shells of the target atom and the ground state of atomic hydrogen formed, Theoretical results are compared with the available experimental data on helium, neon and argon atoms at different energies.
