P. Kleban et I. Peschel, FULLY-FINITE 2-DIMENSIONAL CRITICAL SYSTEMS - CASIMIR TERMS AND INSTABILITIES, International journal of modern physics b, 11(1-2), 1997, pp. 133-139
We review recent results for the universal part of the free energy of
fully-finite two-dimensional regions at criticality. Their effect on t
he total free energy is considered. Including non-universal edge free
energy terms leads to various Casimir instabilities toward elongation,
sharp corner on the boundary, and other behavior. Universal features
of certain matrix elements of the transfer matrix and corner transfer
matrix are also obtained.