a First-Principles Theoretical Description of the Negative-Slope Melting Phenomenon in Group-Iv Semiconductors.

A negative-slope melting curve was calculated for the elements silicon and germanium from first principles. Three adjustable parameters obtained from the theory were chosen to fit the calculated melting point and volumes to experiment at zero pressure resulting in a good fit of the theory to experiment for pressures up to approximately 25 kilobar. The metallic liquid state of these elements was described using the Mansoori-Canfield variational approach with a hard-sphere reference system. The solid state was described by a system consisting of interacting ions, covalent-bond charges, and electrons. A variational approach was also used to describe the solid state.