Molecular Dynamics Simulation of the Flow of Ions and Water Molecules in a Carbon Nanotorus Induced by Rotating Electric Field

Speaker: Dr. Maryam Kosar

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 clever design of
nanoelectronic devices for various prospective applications. Also, new ideas have been proposed for the
application of such a system and transport phenomenon in photodynamic therapy for cancer treatment.
The ability to manipulate fluids at the nanoscale has received growing theoretical, experimental and applied interests, especially in the past decade. Recent experimental measurements of fluid flow through channels with nanometer widths have confirmed predictions derived from computer simulations stating that such a flow occurs faster than expected. Induction and control of fluids in nano-sized spaces including carbon nanotubes for prospective applications in nano- actuators and devices, including medical applications, have received attentions of chemists and physicists.
Among nanofluids studied so far, water has received considerable attention mainly due to its relevant
applications in biological systems as well as its stability and simplicity for prospective nanofluidic device design. There have been several studies on the dynamics of the confined water molecules in a nanotorus in the absence of electric fields. Furthermore, theoretical studies on the effects of electric fields on water molecules in nanotubes have started some years ago. Effects of homogeneous electric fields (EFs) on the static and dynamic features of water molecules in nanostructures like nanotubes have been studied both theoretically and computationally. So far, effects of rotating EFs on the characteristics of water molecules in the bulk state have been studied using MD simulations. The filling structure and the transport characteristics of water molecules confined in carbon nanotori can be considered important because of their potential applications, e.g. in micro/nanoelectromechanical systems (MEMS/NEMS).
The aim of this research is to study the effects of rotating electric fields (EFs) on the cyclotron motion of molecules and ions in a (6,6) carbon nanotorus. To this end, the electric field subroutine of the GROMACS software is modified to include rotating electric fields. Also, after producing structure of the nanotorus, species of interest, i.e. Na+ , K+ and Ca2+ ions, and 81 water molecules, have been placed in the nanotorus space using a Fortran program. In the presence of rotating electric fields, molecular dynamics simulations are carried out on these molecules and ions. Thereafter, response of the ions and water molecules to the EF, their orientations, velocities and dipole moments are investigated. In the next part of this research, the resulted magnetic field and moments induced by the motion of these charged particles are calculated and analyzed.