Ab-initio Calculations on Melting of Thorium

Ab-initio molecular dynamics study has been performed on face centered cubic structured thorium to determine its melting temperature at room pressure. The ion-electron interaction potential energy calculated as a function of temperature for three volumes (a(0))(3) and (1.02a(0))(3) and (1.04a(0))(3) increases gradually with temperature and undergoes a sharp jump at similar to 2200 K, similar to 2100 K and similar to 1800 K, respectively. Here, a(0) = 5.043 angstrom is the equilibrium lattice parameter at 0 K obtained from ab-initio calculations. These jumps in interaction energy are treated as due to the onset of melting and corresponding temperatures as melting point. The melting point of 2100 K is close to the experimental value of 2023K. Further, the same has been verified by plotting the atomic arrangement evolved at various temperatures and corresponding pair correlation functions.