A double exponential potential for van der Waals interaction

Xiongwu Wu,Bernard R. Brooks

doi:10.1063/1.5107505

Abstract

Van der Waals (vdw) interaction is an important force between atoms and molecules. Many potential functions have been proposed to model vdw interaction such as the Lennard-Jones (L-J) potential. To overcome certain drawbacks of existing function forms, this work proposes a double exponential (DE) potential that contains a repulsive exponential term and an attractive exponential term. This potential decays faster than the L-J potential and has a soft core. The DE potential is very flexible and its two exponential parameters can be adjusted continuously to mimic many potential functions. Combined with the isotropic periodic sum (IPS) method, the DE potential can efficiently and accurately describe non-bonded interactions and is convenient for alchemical free energy calculation.

Highlights

The function have a minimum of −ε0 at r = rm. σ is the distance where the potential is zero
Study from the interacting quantum atoms (IQA) method has demonstrated that exponential relationships can better capture atomistic short-range repulsion
The L-J potential diverges when two atoms approach one another, which is a problem for the r6 term of the Buckingham potential. It is found the dispersion interaction can be better described with a damped r6 term, indicating a new way to construct the dispersion component is needed for a new-generation force field

Summary

Introduction

We propose a double exponential (DE) potential of the following form: βeα r αeβ r ε(r) = ε0 exp(−α ) − 17.739 16.262 15.782 15.774 16.016 16.409 16.906 27.837 21.945 18.473 17.083 16.626 16.603 16.809 17.155 17.599 18.119 28.288 22.520 19.235 17.935 17.504 17.470 17.644 17.946 18.341 18.810 19.341 28.749 23.141 20.027 18.817 18.410 18.365 18.510 18.774 19.124 19.545 20.027 20.564 29.227 23.793 20.851 19.724 19.339 19.283 19.401 19.630 19.940 20.317 20.754 21.244 21.785 c scitation.org/journal/adv adjusted continuously to mimic many potential functions.

Results

Conclusion