Theoretical Study of Static and Dynamic Equation of State of Cerium and Ytterbium

Theoretical study of the dynamic equation of state or shock Hugoniot plays a key role in describing behaviour of materials under simultaneous high temperature and high pressure that are very difficult to achieve in the experiments. Schock Hugoniot is locus of all possible states that arises due to a single shock from a given initial state, generally explained by thermodynamic variables like pressure, volume and internal energy or enthalpy. Anharmonicity aroused due to lattice ions and thermally excited electrons should be accounted properly at such high temperature and high pressure. In the present study, a conjunction scheme of a local form of the pseudopotential proposed by Krasko and Gruski (KG) and mean field potential (MFP) has been used to account anharmonic effects due to lattice vibrations. The anharmonicity due to thermally excited electrons has been included using Mermin functional. Static as well as dynamic equation of states along with temperature along principal Hugoniot of rare earth elements cerium and ytterbium have been studied theoretically. The conjunction scheme is found to be capable to account for anharmonicity at extreme environment such as high temperature and high pressure.