Mean-field potential approach to the quasiharmonic theory of solids

Adopting the quasiharmonic approximation, a newly developed classical mean-field potential (MFP) approach is extended to the quantum case. Two new Debye temperature expressions, which are in accordance with the thermodynamic theory of Dugdale and MacDonald and with the free volume theory, respectively, are derived in addition to the well-known expression of Slater. The Grüneisen law is now implied explicitly in the Debye temperature expression, and therefore no additional conditions for the Grüneisen constant are needed for realistic thermodynamic calculations. The thermal expansion and specific heat of Na, Cu, Mo, Ta, and Th have been calculated from 10 K up to the melting point.