Correlation between the temperature dependence of the band gap and the temperature dependence of the enthalpy of semiconductor crystals

The first-principles pseudopotential method of density-functional theory is used to study electron-phonon interactions in silicon. The temperature shift of the indirect band gap, the phonon spectrum, and the enthalpy are calculated consistently within the density-functional theory. The relationship between the temperature dependence of the energy gap Delta E-g (T) and the temperature dependence of the enthalpy Delta H(T) is Delta H(T) = K\D Delta E-g (T)\. The physical origin of this correlation is discussed. (C) 1998 American Institute of Physics. [S1063-7826(98)00109-4].