Computer Simulation Study Of The Mechanical Properties And Surface Stability Of Hydrogen Molecular Crystal

In recent years,with the gradual development of modern science,various new energy technologies have been continuously researched and developed.Among them,the most efficient,energy-saving and environmentally-friendly nuclear energy has been widely studied and applied by many countries.Due to the low cost and rich storage of raw materials required for nuclear fusion reactions,nuclear fusion reactions are considered to be an effective way to solve energy problems.Inertial Confinement Nuclear Fusion?ICF?^[1]is one of the nuclear fusion reactions that uses a high-power laser to rapidly heat a deuterium-tritium?D-T?fuel pellet in a very short period of time to achieve a nuclear fusion reaction.During the reaction process,the design rationality of the target capsule determines the success of the fusion reaction and the energy output.Therefore,the full study of the mechanical properties of hydrogen molecular crystals and the stability of the surface structure of the pellets are valuable for the rational design and preparation of D-T pellets with excellent properties.In this paper,the molecular dynamics method and the MOLDY software are used to systematically study the mechanical properties and surface stability of hydrogen molecular crystals.The research results are as follows:1.This paper analyzes and studies the related theory of hydrogen intermolecular interaction potentials and the characteristics of various potentials.Using the molecular dynamics method,the zero point energy can be taken into account,and the potential interactions between hydrogen molecules proposed by Silver and Goldman?S-G potential?are improved and the parameters are fitted to a suitable H₂-H₂ potential for hydrogen molecular crystals.2.Based on the modified potential of S-G,this paper focuses on the calculation of related parameters of hydrogen crystals in hcp structure.A comparison of the calculated results to previous results shows that the modified S-G potential is credible and reliable,which lays the foundation of the molecular dynamics?MD?method used in this study to simulate mechanical properties of hydrogen crystals and the surface stability of the pellets.3.In order to study the mechanical properties of hydrogen or molecular crystals,this article has undergone a lot of simulation calculations,and the specific work is as follows:a solid ball-like pellet model with a radius of 150?has been used to study the mechanical properties of,hydrogen or deuterium molecular crystals by using the molecular dynamics method and the modified S-G potential.The calculated elastic constants and bulk modulus of the hydrogen or deuterium molecular crystals at 0 K and0 bar are compared with experimental results and other's theoretical calculations,which proves that the potential and the calculation method used in this work are feasible.On this basis,the mechanical constants,such as the elastic constants and the bulk modulus of the hydrogen molecular crystals and the deuterium crystals from 0 kbar to 10 kbar,were further calculated.The results show that the elastic constants and elastic modulus increased with the increasing of pressure.The mechanical properties of deuterium crystals are slightly stronger than that of hydrogen crystals.4.The stability of the inner and outer surfaces of spherical shell target capsules of hydrogen or deuterium crystals was studied,and the surface roughness was used to quantitatively characterize the degree of surface structure change.Spherical shell models of different sizes was established for the hydrogen or deuterium crystals,respectively,and external factors such as pressure and temperature were taken into consideration.Using our potential and MD methods,we calculated the roughness of the inner and outer surfaces of spherical shell of hexagonal close-packed hydrogen or deuterium molecular crystals with different sizes.The results show that the roughness increases with increasing pressure,and increases with the decrease of temperature,which is basically consistent with the previous experimental results.