The Ising model on a cylinder: universal finite size corrections and   diagonalized action
  Finite size corrections to the pressure (free energy) of the Ising model on a 2 dimensional cylinder are calculated and shown to be consistent with the predictions of conformal field theory. The exact solution of the model is expressed in terms of the determinant of a block-diagonal matrix. 
Rafael L. Greenblatt
cond-mat.stat-mech math-ph math.MP