Many-body Contributions Among Solid Argon&Their Influences To The High-pressure Equations Of State, The Study Of Statistical Mechanics Model Of Hydrogen Plasma At High Temperature And High Pressure

This article describes two research projects:Many-body contributions among solid argon&their influences to the high-pressure equations of state, the study of statistical mechanics model of hydrogen plasma at high temperature and high pressure.The argon has a relatively simple full-shell electronic structure, making it is a typical system to study the properties of condensed matter at high pressure. In addition, argon is transmission medium in the static pressure experiments. Therefore, the study of the quantum theory of high-pressure argon has been one of the topics of interest in condensed matter physics.Hydrogen is diatomic molecules at room temperature and atmospheric pressure, and it occur ionize and form plasma at the high temperature and high pressure. Using quantum statistical theory and its simulation results to construct the free energy model of statistical mechanics, it is great significance to understand the properties under high temperature and pressure.Based on the many-body expansion method and the double cluster with full single and double excitations plus perturbative treatment of triples (CCSD(T)), we obtain the three-and four-body interaction contribution to cohesive energy and the equation of state of solid argon in a wide range compression by using Ab initio calculation of three- and four-body interaction contribution energy for compressed solid argon. The main research works are:(1) the two-, three-and four-body interactions’contribution to cohesive energy of fcc argon,(2) the zero-point vibrational energy, and (3) their impact on the equations of state. We also give theoretical equation of state of the density functional theory based on the local density approximation (LDA) and generalized gradient approximation (GGA) fcc solid argon. Traditional density functional theory are certain difficulties in describing the inert atoms interaction, especially the van der Waals force; it does not give satisfactory explained for equation of state data of tens of GPa pressure range (P<-50GPa), and can only give a satisfactory description of the experimental data at the high pressure zone. The results show that many-body method and CCSD (T) calculation is much overestimated if only two-body interactions are included, but our work basically agreement with experiments at the whole studied range0-114GPa when the three-body corrections are added to. When the pressure up to114GPa, the difference only have3GPa between our result and experimental data; when taking into account the four-body interaction, the many-body expansion theory and density functional theory results at the high pressure range from50to200GPa.In the study of hydrogen plasma at high temperature and high pressure, we construct a theoretical model of the equation of state of hydrogen plasma by studying of the thermodynamic properties of full ionized region of hydrogen. and We study charged ions and electrons system using Stolzmann and Chabrier’s ionized plasma model and construct the Helmholz free energy function F({Ni},V,T){i=H+, e-} of multi-component system, while we obtain the internal energy and the pressure of the system by the thermodynamic relations.