Many-body Contributions Among Solid Neon And Krypton&Their Influences To The High-pressure Equations Of State

The condensed matters of rare gas elements have been among the widely studied materials, both theoretically and experimentally. Due to the weakness of van der Waals interactions between atoms, the density-functional theory(DFT) is not enough accurate to account for both the long-range dispersive interactions and the short-range overlap effects. The importance of these systems lies in the fact that they are relatively simple to study due to their closed-shell electronic structure.Based on the atomic cluster theory and quantum chemical theory, the various many-body correlations among atoms in condensed neon and krypton have been investigated, then the high-pressure equation of state is given, and the compression dependence of the many-body interactions are revealed. The main research works are:(1) the two-, three-and four-body interactions’contribution to cohesive energy of fee neon and krypton,(2) the zero-point vibrational energy, and (3) their impact on the equations of state.The present calculations show that, when the nearest atomic distance R in solid neon is in the range of2.7-2.6A, the many-body expansion series can be truncated at two-body term to fit the cohesive energy; when R is between2.6and1.9A, three-body term must be considered; when R is reduced to1.7A the four-body interaction needs to be taken in account, when the potential energy is expanded to the three-body term, the theoretical result can better explain current experiment data(0-208GPa). For solid krypton, when R is in4.0～3.1A, the many-body expansion series can be truncated at three-body term; when R less than3.1A, four-body term must be considered, it can correct the overestimation of the negative three-body interaction. Considering the two- to four-body potentials, the theoretical results can successfully take account the current experimental pressure data(0-103GPa).