Study On A Hydrogen Molecule Under High Pressure And High Pressure Joint With Strong Magnetic Field

Hydrogen is the most abundant and simplest element in the universe,and its research has always been one of the core issues in the field of high-pressure physics.In this thesis,we take hydrogen molecules as the research object,and use the ellipsoid model to study the effect of pressure and pressure joint with magnetic field on the properties of hydrogen molecules.In order to understand the internal behavior of the hydrogen molecule more realistically,the influence of the movement of the nucleus on the behavior of hydrogen molecule was fully considered,and the accurate simulation was carried out by using the Quantum Monte Carlo method.,we found:By fully considered the he movement of the atomic nucleus,it can reflect the influence brought by the difference in atomic nucleus quality,that is,the difference in isotopes.Compared with the predecessor fixed nuclear model,our hydrogen /deuterium model has higher total energy and pressure at the same molar density,and has lower compressibility and more complex geometric change law,such as bond length,the long axis / short axis of ellipsoid.Whether hydrogen or deuterium,the kinetic energy of their nuclei is in the order of one-thousandth of an electron,but the movement of the nuclei affects the total energy,especially under high pressure.At the same molar density,the total energy and pressure of hydrogen are higher than those of deuterium.We found that there are numerical relationships between some physical quantities,such as the linear relationship between the total energy of a molecule and the reciprocal of the volume of the ellipsoid of the confined molecule,and the linearrelationship between the pressure of the system and the square of the number of moles of density.Deuterium and hydrogen have great differences in compressive properties such as bond length compressibility,topological properties of bound ellipsoid,etc.,which may explain the difference in their phase diagrams and the unique ?' and II'phases of deuterium.In the presence of a magnetic field,the total molecular energy is higher than when there is no magnetic field under the same bound volume,and the proportional relationship between the total energy of the system and the reciprocal of the volume can continue to a smaller bound volume;There is still a proportional relationship between the pressure and the square of the density;In the presence of a magnetic field,the hydrogen molecular bond length is shorter at the same pressure,which is more obvious at lower pressures;In the case of magnetic field,the electron kinetic energy is improved in the case of the same bound volume.On the curve of the relationship between the electron kinetic energy and the reciprocal volume,three regions can be clearly seen,the nuclear kinetic energy shows a stepped change corresponding to the three regions.The interaction potential energy between electron and nucleus decreases,especially at low pressure,while the interaction potential energy between nuclei and between electrons increases.In the shape change of ellipsoid,magnetic field is similar to that in the absence of magnetic field.The above research provides help to understand the difference in phase diagrams of different hydrogen isotopes under pressure,corrects calculations based on adiabatic approximation such as density functional,and provides data support for understanding the state of hydrogen under strong magnetic fields.