How the vibrational frequency varies with temperature

A renormalization of mode wavenumber with temperature in inorganic (silicon, diamond) and molecular crystals (α-S₈) is considered. The conventional theory of wavenumber varying is based on phonon decay into other phonons. A new approach based on the process of phonon excitation and analytical expression for ω(T) function is proposed. A numerical quantity of anharmonic contributions from vibration of chemical bonds of different types is discussed. It is shown that anharmonicity of hydrogen bonds is essentially higher than that of the other types of chemical bond.