Phase stability of actinide carbides

Abstract

Electronic, structural, mechanical, magnetic and thermodynamical properties of uranium and thorium sesquicarbides (U2C3 and Th2C3) were investigated by the means of first principles calculations, with special interest in the effects of 5f electrons. Utilized models included various approximations of exchange-correlation electronic terms, spin-orbital interaction (with a major effect on U2C3 and negligible effect on Th2C3) and Hubbard U model for electronic Coulomb interaction. The magnitude of these effects is demonstrated on the direct comparison of various physical quantities, such as enthalpy of formation, magnetic ordering, heat capacity, elastic constants, etc. and compared with experimental data.