Theory of the thermal expansion of Si and diamond

Abstract

Phonon-dispersion curves, lattice mode Gr\"uneisen parameters, and the coefficients of thermal expansion are calculated for Si and C within a tight-binding model. The results are in good agreement with experimental data. The origin of the negative thermal expansion in Si is examined, and we find that the different thermal-expansion behaviors between Si and C can be explained by the different relative strengths of bond-bending and bond-stretching forces.