FOLDING TRANSITION OF THE TRIANGULAR LATTICE IN A DISCRETE 3-DIMENSIONAL SPACE

A vertex model introduced by M. Bowick, P. Di Francesco, O. Golinelli, and E. Guitter [Nucl. Phys. B 450, 463 (1995)] describing the folding of the triangular lattice onto the face centered cubic lattice has be en studied in the hexagon approximation of the cluster variation metho d. The model describes the behavior of a polymerized membrane in a dis crete three-dimensional space. We have introduced a curvature energy a nd a symmetry breaking field and studied the phase diagram of the resu lting model. By varying the curvature energy parameter, a first-order transition has been found between a flat and a folded phase for any va lue of the symmetry breaking field.