Lowest-order approximations to relaxation volumes of monovacancies in cubic metals from pair potentials and Finnis-Sinclair potentials By W. MAYSENH~LDER

Relaxation volumes of point defects in cubic metals can be conveniently estimated by differentiating approximate formation energies with respect to the lattice constant. Lowest-order analytical expressions for monovacancies have been derived for equilibrium pair potentials and for the N-body potentials of Finnis and Sinclair (1984). Thesc expressions may be evaluated with little effort and prove far superior to other lowest-order approximations to vacancy relaxation volumes. Vacancy relaxation volumes provide a stringent test of the quality of interatomic potentials which are supposed to yield reliable information about lattice defects. A classical example is the monovacancy in copper, for which all central equilibrium pair potentials failed to reproduce the experimental relaxation of about- 0.2 atomi