Two types of three-particle interactions and their influence on elastic constant temperature dependence

A new phenomenological model of particle interaction energy is created for crystals characterized by B 1 and B 2 cubic structures. The model incorporates isotropic pair Lennard-Jones coupling and two types of anisotropic three-particle interactions. The three-particle interactions are of the same symmetry but of different natures, which is reflected in their dependence on the vectors joining two particles. The model allows a qualitative description of NaCl, KCl, KY, KBr elastic constants differences δ = C xxyy − C xyxy .