Protocol for classical molecular dynamics simulations of nano-junctions in solution

Abstract

Modeling of nanoscale electronic devices in water requires the evaluation of the transport properties averaged over the possible configurations of the solvent. They can be obtained from classical molecular dynamics for water confined in the device. A series of classical molecular dynamics simulations is performed to establish a methodology for estimating the average number of water molecules N confined between two static and semi-infinite gold electrodes. Variations in key parameters of the simulations, as well as simulations with non-static infinite gold surfaces of constant area and with anisotropically fluctuating cell dimensions lead to less than 1% discrepancies in the calculated N. Our approach is then applied to a carbon nanotube placed between the gold electrodes. The atomic density profile along the axis separating the slabs shows the typical pattern of confined liquids, irrespective of the presence of the nanotube, while parallel to the slabs the nanotube perturbs the obtained profile