Properties of Thorium Compounds: Application of Interionic Potential Theory

In the present work structural and mechanical properties of ThC and ThO compounds have been carried out using desirable modified inter-ionic potential theory (MIPT), which parametrically includes the effect of Coulomb screening. The transition from rock salt to caesium chloride occurs around 40.0 GPa and 65.0 GPa in the case of ThC and ThO respectively. We have also calculated bulk (B0), Young (E), and shear moduli (G), Poisson ratio (υ) and anisotropic ratio (A) in NaCl-type structure for these compounds and differentiate them with other experimental and theoretical results which show a good agreement.

MOLECULAR DYNAMICS SIMULATION OF UO2: AN ALTERNATIVE RIGID ION MODEL POTENTIAL

A semi-empirical effective interionic potential model has been parameterized to investigate UO 2 by molecular dynamics simulation technique. The simulations were performed in the constant pressure–temperature ensemble between 300 K–3200 K at 100 K intervals. The pair distribution functions and coordination numbers signal the onset of structural changes at temperatures in accord with the Bredig transition and melting. The oxygen ion diffusion coefficients calculated from the mean square displacements markedly increase the liquid like value at T > 2100 K . The transition to the superionic state and melting are well reproduced within the limitations of a rigid ion potential.

A STATISTICAL MECHANICAL STUDY OF THERMODYNAMIC PROPERTIES OF SOLID SODIUM UNDER PRESSURE BASED ON AN EFFECTIVE INTERIONIC POTENTIAL

Basing on the Schiff effective interionic potential that has an oscillatory character and the correlative method of unsymmetrized self-consistent field (CUSF) that enables one to take into account the strong anharmonicity of the crystal lattice vibrations, we have calculated a complete set of equilibrium thermodynamic properties of solid sodium as functions of pressure and temperature: the lattice parameter, the elastic moduli, the thermal expansion coefficient, the Grüneisen parameter and the isochoric and isobaric heat capacities. Our results are compared with available experimental data. We also discuss the thermodynamic stability of the BCC lattice, the mechanism of its loss and its change under pressure.