Development of a Charge-Implicit ReaxFF Potential for Hydrocarbon Systems

Molecular
dynamics (MD) simulations continue to make important
contributions to understanding chemical and physical processes. Concomitant
with the growth of MD simulations is the need to have interaction
potentials that both represent the chemistry of the system and are
computationally efficient. We propose a modification to the ReaxFF
potential for carbon and hydrogen that eliminates the time-consuming
charge equilibration, eliminates the acknowledged flaws of the electronegativity
equalization method, includes an expanded training set for condensed
phases, has a repulsive wall for simulations of energetic particle
bombardment, and is compatible with the LAMMPS code. This charge-implicit
ReaxFF potential is five times faster than the conventional ReaxFF
potential for a simulation of keV particle bombardment with a sample
size of over 800 000 atoms.

分子动力学（MD）模拟在理解化学与物理过程方面持续发挥着重要作用。随着MD模拟技术的不断发展，对能够既体现系统化学特性又具备高效计算性能的相互作用势的需求亦日益增长。本文提出对碳氢元素适用的ReaxFF势函数的改进，该改进消除了耗时耗力的电荷平衡过程，摒弃了公认的电子亲和度均衡方法的缺陷，扩展了凝聚相的训练集，为高能粒子轰击模拟提供了排斥壁，且与LAMMPS代码相兼容。此电荷隐式ReaxFF势函数在模拟keV粒子轰击并包含超过800,000个原子的样本时，其计算速度比传统ReaxFF势函数快五倍。