Stable pair potential
= Stable pair potential
{title2=$\sum_{i<j}v(r_{ij})\ge-BN$}
A <pair potential> is stable when its total interaction <energy> obeys this lower bound for every allowed configuration, with a constant $B$ independent of $N$. It prevents collapse with an arbitrarily negative <energy> per particle. Stability alone does not control the long-distance contribution needed for the ordinary <thermodynamic limit>.