Optimized utilization of COMB3 reactive potentials in LAMMPS

TL;DR

This study optimizes the use of COMB3 reactive potentials in molecular dynamics simulations, focusing on parameters like time step and charge equilibration to improve accuracy and efficiency in modeling water copper interactions.

Contribution

It introduces optimized simulation parameters for COMB3 potentials, enabling longer time steps and reduced computational cost without sacrificing accuracy.

Findings

Longer time steps of 0.4 fs are feasible with extended temperature relaxation.

Charge equilibration can be performed less frequently without loss of accuracy.

Wetting rates are highly sensitive to temperature relaxation times.

Abstract

An investigation to optimize the application of the third-generation charge optimized many-body (COMB3) interatomic potential and associated input parameters was carried out through the study of solid-liquid interactions in classical molecular dynamics (MD) simulations. The rates of these molecular interactions are understood though the wetting rates of water nano droplets on a bare copper (111) surface. Implementing the Langevin thermostat, the influence of simulation time step, the number of atoms in the system, the frequency at which charge equilibration is performed, and the temperature relaxation rate are all examined. The results indicate that time steps of 0.4 fs are possible when using longer relaxation times for the system temperature, which is almost double the typical time step used for reactive potentials. The use of the QEq charge equilibration allows for a fewer atomic layers to be used in the Cu slab. In addition, charge equilibrium schemes do not need to be performed every time step to ensure accurate charge transfer. Interestingly, the rate of wetting for the nanodroplets is dominantly dependent on the temperature relaxation time which are predicted to significantly change the viscosity of the water droplets. This work provides a pathway for optimizing simulations using the COMB3 reactive interatomic potential.