Hybrid potential model with high feasibility and flexibility for metallic and covalent solids

Abstract

Pair-functional potentials are generally used for metallic solids, whereas cluster potentials are more appropriate for covalent solids; however, both face critical difficulties that cannot be solved based purely on the optimization of potential functions, e.g., the lattice stability for hcp metals with high c/a ratios and the conflict between stacking-fault energy and cleavage energy for covalent solids, which can be attributed to their respective physical foundations and approximations according to their bonding characteristics. By incorporating the long-range many-body effect in pair-functional potentials and the short-range angular-dependent terms in cluster potentials, a unified hybrid potential model is physically justified and proposed in the present study for both metallic and covalent bonding solids to resolve the aforementioned critical issues and other specific cases. The proposed model was not only successfully demonstrated for a series of elemental solids, including 20 fcc, bcc, and hcp metals and three covalent elements, but also was extended to construct cross potentials for three representative compound systems, i.e., CuNi, TiC, and BN, which suggests that the present hybrid potential model possess higher compatibility and feasibility for various metallic and covalent systems than the respective pair-functional potentials and cluster ones. Overall, the hybrid potential model not only complements the current potential library but also builds a foundation for further potential development with high flexibility.