  Continuing the arguments in Paper I (arXiv: cond-mat/0405487), we model the
temperature dependence of interstitial defects in a surface-free
face-centered-cubic (fcc) elemental crystal and obtain the free energy and
correlation behavior based on variational methods. We show that the avalanche
of interstitial defects is the instability mechanism at the melting point that
bridges Lindemann and Born criteria.
