Vibrational entropy in static simulations of point defects

A new procedure for computing the vibrational entropy in point defect simul ations is presented. The method rests on including in the calculations all the atoms whose frequencies are influenced by the defect field. This develo pment is motivated by the failure of the previous graphical extrapolation m ethod when applied to crystallite sizes accessible to nowadays hardware:. T he analysis carried out here also provides a consistent dilation coefficien t to use, e.g., for correcting entropies from fixed volume to fixed pressur e calculations, while performing static simulations, strictly valid at 0 K. Any semiempirical interatomic potential currently in use should be able to benefit from this technique.