Finite-temperature properties of perfect crystals and defects from zero-temperature energy minimization

A method for calculating the thermodynamic properties of both classical perfect crystals and defects by performing a single zero-temperature energy minimization is described. This method is based upon the calculation of a local harmonic free energy as performed by LeSar et al. and by Sutton, and involves determining the dynamical matrix, Gruneisen parameters, and the elastic properties of the system. The dependence of the free energy and the lattice parameter of a perfect Au crystal on temperature are accurately determined with this method. The validity of this method is demonstrated by accurately determining the temperature dependence of the vacancy formation energy, the excess free energy of a (100) surface, and the excess free energy of a ∑13 (001) (22.62º ) twist grain boundary.