Equation Of State And Elastic Modulus Calculation For Uranium And Uranium Dioxide

Both uranium and uranium dioxide are key materials with complex electronic behaviors in the fields of nuclear science and nuclear engineering,and have attracted great researching interests.For a long time,researches have conducted enormous studies on their physical properties,among which we pay special attentions to the equation of states(EOS)and the elastic modulus.The former describes the basic relationships between the physical quantities of materials,and the latter is one of the important properties of solid materials in practical applications.For many years,people have used different experimental techniques to study the EOS and elastic modulus of uranium and uranium dioxide.However,certain experimental data,especially the elastic modulus data is still insufficient,due to the special properties of uranium and its compounds.Since the 1990s,the first-principles calculation method based on density functional theory(DFT)has been developing rapidly,and the prediction and/or verification of the physical properties of materials by this method has become a hot research topic.In this thesis,in virtue of the first-principles calculation method,the DFT(+U)method and Debye model are used to study the EOS at zero and finite temperatures theoretically.Additionally,we have developed a set of software to calculate the elastic modulus autonomously.Based on this software,we have calculated the elastic modulus of uranium and uranium dioxide under high pressure,which were still lacking experimentally.