COLLAPSE OF AN ALTERNATING POLYAMPHOLYTE - EVIDENCE FOR TRICRITICALITY IN 2 AND 3 DIMENSIONS

We show numerical evidence in 2 and 3 dimensions that an alternating polyampholyte undergoes a coil-globule transition as the temperature decreases and that this transition is nothing but a THETA-point. Tricritical exponents and scaling laws are found to be in very good agreement with those of a regular THETA-point. An analytic expression is derived for the mean potential between charged monomers which proves the short-range nature of the effective interactions, thus supporting our numerical conclusions.