Calculation of theoretical strengths and bulk moduli of bcc metals

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Abstract
A first-principles method based on the local-density approximation using discrete variational clusters has been used to study the electronic structure of bcc metals, Li, Na, K, V, Nb, Ta, Cr, Mo, and W. The binding energy of these metals was calculated, and the relationship between the binding energy and the volume of a unit cell for a given metal was determined. The results show that the contribution of the interaction beyond the third nearest-neighbor atoms to the binding energy is small for transition metals, but large for alkali metals. The theoretical triaxial tensile strength and bulk modulus of these metals were estimated from the electronic structure and binding-energy calculations. The present results of the bulk modulus for Li, Na, K, Nb, Ta, Mo, and W are in good agreement with experiments and other available theoretical data, but the bulk modulus for V and Cr is somewhat overestimated. The theoretical strength obtained in the present work is in good agreement with the results of the linear muffin-tin-orbitals method.