Molecular dynamics simulation of the cyclotron motion of ions in a carbon nanotorus induced by gigahertz rotating electric field

Abstract

Molecular dynamics (MD) simulations of the transport of ions in nano-confined spaces such as nanotori, which can be regarded as a good analogue of ion accelerators and cyclotrons, can help smart design of nanoelectronic devices for various prospective applications including local control of electron transfer, switching molecular and nano circuits and also photodynamic therapy. In this regard, a cyclotron motion is established for the Na+, Ca2+ and K+ ions inside a rigid carbon nanotorus by applying gigahertz homogeneous rotating electric fields (EF) of 0.01–1.00 V/nm strengths and 16–128 GHz frequencies. The ion-wall collisions result in a fluctuation in the instantaneous position of the ions lagging behind the direction of the EF. Analysis of the variations of the position vector of the ion with respect to the instantaneous direction of the EF, measured in terms of the lagging angle (Formula presented.), shows that for all three ions, narrow distributions towards the desired value of (Formula presented.) are achieved by increasing strength and decreasing frequency of the EF. Under similar conditions, average values of the acquired velocities of ions follow the order: (Formula presented.) which reflects their relative charge/mass ratios and interactions with the nanotorus carbon atoms. The results show that, more stable motion could be obtained with stronger EF and lower frequency. Lighter ions with higher electric charge are more appropriate for the induction of nanocyclotron motion. Continuous cyclotron motion could also be established with the relaxed nanotorus and in a nanotorus of larger radius. © 2017 Informa UK Limited, trading as Taylor & Francis Group.