Notes on the dynamic interlayer potential of oriented FCC crystals

he simplest possible model of interatomic potential, a harmonic one, is used to find out an analytical approximation of the interlayer potential in oriented FCC crystals by using a series expansion of the potential near its
minimum of energy. That dynamic interlayer potential is caused by mutual displacements of neighboring layers. The result is, however, nontrivial due to its complexity and mathematical richness. It is shown that the potential may be treated as a generalization to 3D of the classical 2D Hénon-Heiles potential that significantly contributed to the development of the theory of chaos