CLUSTER APPROACH TO 1ST-PRINCIPLES THERMODYNAMICS OF CRYSTALS

Total energy density-functional methods have made it possible to calcu late, from first principles, such important properties as cohesive ene rgies, lattice constants and elastic moduli for elemental crystals and perfectly ordered compounds. Real solids are imperfect, however, so t hat lattice vibrations and compositional disorder lead to entropy cont ributions, vibrational and configurational. When these effects are inc luded in an appropriate manner, properties of real crystals can be com puted ab initio as a function of temperature and concentration. Conseq uently, it is possible to obtain, virtually from the knowledge of atom ic numbers alone, such basic thermodynamic properties as free energies , entropies, heats of formation, and lattice parameters for stable and metastable phases, leading, for example, to the successful computatio n of certain classes of phase diagrams. Recent progress in the field w ill be reviewed.