Interatomic Interaction Potential Function Theory And Application Of Research

The subject of the dissertation is about the "interatomic potential", which includes theoretical analyses and some new applications of intratomic potentials.Based on the Green's function of tight-binding representation, we deduced the analytical form of many-body interatomic potentials. The many-body potentials are expressed as the functions of the hopping integrals, which are the physical origin of cohesion of atoms. A simple potential model including pair- and three-body interactions is proposed for the simple case of s-valent system and applied to BCC alkaline metals.Recently, M(o|¨)bius inversion in number theory has been modified and used to treat some important inverse problems, particularly, the lattice problems in physics. Using this so-called lattice inversion method(LIM), a simple scheme for the inversion of pair potentials between the distinct atoms in alloys is discussed in detail and a possible approach for the inversion of the many-body potentials is also discussed.Recently, there has been considerable interest in the physical origin and the role of the difference in vibrational entropy between different states of materials since it was found by experimental measurements that the vibrational entropy difference between ordered and disordered phases might be a sizable fraction to the total entropy difference. Using a combination of first-principle calculations and the lattice inversion method, we calculated the difference in vibrational entropy between chemically disordered and ordered Fe — Al compounds and the calculated results are in good agreement with experimental data. The physical origin of the difference in vibrational entropy, the existence of the high energy optical mode in ordered crystal resulting in the lower entropy of the ordered, was revealed.Metal hydrides have attracted a lot of attentions in both fundamental and applied re-...