Molecular dynamics study of melting of a bcc metal-vanadium I: mechanical melting

摘要

We present molecular dynamics simulations of the homogeneous (mechanical)melting transition of a bcc metal, vanadium. We study both the nominallyperfect crystal as well as one that includes point defects. According to theBorn criterion, a solid cannot be expanded above a critical volume, at which a'rigidity catastrophe' occurs. This catastrophe is caused by the vanishing ofthe elastic shear modulus. We found that this critical volume is independent ofthe route by which it is reached whether by heating the crystal, or by addinginterstitials at a constant temperature which expand the lattice. Overall,these results are similar to what was found previously for an fcc metal,copper. The simulations establish a phase diagram of the mechanical meltingtemperature as a function of the concentration of interstitials. Our resultsshow that the Born model of melting applies to bcc metals in both the nominallyperfect state and in the case where point defects are present.