Conversion of Cv [ T, V ( T )] to Cv [ T, V (0°K)] with Application to Na and Cu

The thermodynamic quantity E(T)= ∫ V0V(∂Cv/∂V)TdV=Cv[T,V(T)]−Cv[T,V(0∘K)]may be evaluated in terms of the thermal expansion and the coefficients, ai's, in the solid equation of state and their derivatives. Slater's procedure for E(T) is extended herein to the case in which the ai's are arbitrary functions of temperature and pressure. This E(T) is then transformed to a second equivalent form in terms of the bulk modulus and its temperature and pressure derivatives. It is seen that Cv[T, V(0)] may be determined entirely from experimental data. The lattice specific heat CL[T,V(0)]=Cv[T,V(0)]−Tγe[V(0)], this form being the physically correct way of calculating CL from electronic specific heat measured at low temperatures, is determined for Na and Cu. The CL[T, V(0)] of Na is compared with the Born—von Kármán theoretical Ctheoret calculated by C. B. Clark; this comparison indicating an anharmonic CL of the form Ctheoret (1+AT+BTn), (5