Theoretical Study of Energy Gap for Silicon and Germanium Under High Pressure

In this study the energy gap (Eg) for both silicon and germanium under high pressure and different temperatures is evaluated using two approaches. One of them by evaluating the gradient of (Eg) with pressure (dEg/dP), and with temperature (dEg/dT) under different pressures. The other, by using different equation of state (Birch-Murnaghan, Misra-Goyal, Vinet and modified Lennard-Jones) to evaluate the variation of lattice constant with pressure, and then evaluate the variation of (Eg) with pressure.