Modification of a ReaxFF potential at short range for energetic materials
Weiyi Li, Tao Wang, Wenhua Li, Jintao Wang, Wanxiao Guo, Zexin Jiang, Yilin Fang, Xiyao Yun, Ning Gao
Abstract
The ReaxFF can describe the properties of energetic materials (EMs) at equilibrium state, but does not work properly in simulating high-energy particle irradiation process because of its weak short-range interaction. In this paper, a modification was made for such a potential by connecting Ziegler-Biersack-Littmark (ZBL) potential to ReaxFF-lg through comparing to Density Functional Theory (DFT) results to accurately describe short-range interactions. After modification, the newly fitted ReaxFF-lg/ZBL potential predicts better the equation of state for EMs In displacement cascade simulations, comparing to results from ab initio molecular dynamics (AIMD), ReaxFF-lg/ZBL presented the similar transferred energy from a primary knock-on atom to surrounding atoms, better than the original ReaxFF-lg potential. Further large-scale displacement cascade simulations indicated ReaxFF-lg/ZBL could be applied for cascade simulations with PKA energy from less than 1 keV to high energy (e.g. 35 keV) cases, which is suitable for effectively simulating high-energy displacement cascades in EMs using molecular dynamics method.