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Thermodynamical properties of solids from microscopic theory: applications to MgF2 and Al2O3

1996; Elsevier BV; Volume: 368; Linguagem: Inglês

10.1016/s0166-1280(96)90571-0

1872-7999

M. A. Blanco, Ángel Martín Pendás, E. Francisco, J. M. Recio, R. Franco,

Thermal and Kinetic Analysis

We have recently developed a non-empirical Debye-like model for the inclusion of thermal effects in the equation of state (EOS) of solids. This model allows the calculation of many thermodynamical properties from the E-V relationship. We report the results of a theoretical investigation that explores the EOS of two ionic solids: MgF2 and Al2O3. The interionic interactions are modelized using either the ab initio Perturbed Ion (aiPI) method or the electron gas formalism along with aiPI electronic wavefunctions, which are allowed to relax with crystal strains. Our EOS results are in overall good agreement with experimental data. Other thermodynamic properties behave in the same way, although Grüneisen constant and related quantities have significant errors. This may be caused by numerical inaccuracies on the high order derivatives needed for its calculation.