On the mechanism of melting in simple metals

Molecular dynamics simulations of aluminum demonstrate a significant increase in the vibrational entropy of formation of interstitial defects having the dumbbell configuration near the melting point $T_m$. Using this result and estimating the density of such defects in the melt by three independent methods, the configurational component of the entropy of the system with defects is determined. It is found that about 70% of the total entropy of melting (and, hence, of the heat of fusion) observed in experiments can be attributed to the generation of interstitial dumbbells at $T=T_m$.