The roles of continuum linear elasticity and atomistic calculations in determining the formation volume and the strain energy of formation of a point defect in a crystal were considered. This was of special relevance to defect formation under stress. The elasticity treatment was based upon the Green's-function solution for a center of contraction or expansion in an anisotropic solid. It made possible a precise definition of a formation volume tensor and led to an extension of Eshelby's result for the work done by an external stress during the transformation of a continuum inclusion. Parameters necessary for a complete continuum calculation of elastic fields around a point defect were obtained by comparison with an atomistic solution in the far-field. However, an elasticity result made it possible to test the validity of the formation volume that was obtained via atomistic calculations under various boundary conditions. It also gave the correction term for formation volume calculated under these boundary conditions. By using 2 types of boundary conditions used in atomistic calculations, a comparison was also made of the strain energies of formation predicted by continuum elasticity and atomistic calculations. The limitations of the continuum linear elastic treatment were revealed by comparison with atomistic calculations of the formation volume and strain energies of small crystals enclosing point defects.

The Continuum Elastic and Atomistic Viewpoints on the Formation Volume and Strain Energy of a Point Defect. K.Garikipati, M.Falk, M.Bouville, B.Puchala, H.Narayanan: Journal of the Mechanics and Physics of Solids, 2006, 54[9], 1929-51