Vibration spectrum and specific heats of copper by de launay's method

A calculation is presented of the specific heat of copper which allows, on the basis of de Launay's model, for the effect of electron‐lattice interactions over the whole of the vibrational spectrum. The first Brillouin zone is divided into 1000 cells which give rise to 3000 frequencies all of which can be obtained from 48 frequency calculations by using the symmetry properties of the lattice. The resulting specific‐heat θ is in very good agreement with experiment at low temperatures, but at high temperatures θ is found to be about 3% higher than the experimental value.