THETA-STATE AND COLLAPSE OF OFF-LATTICE CHAINS IN 2 DIMENSIONS

We have performed a Monte Carlo study of dimensions for two dimensiona l linear chains of different lengths. These chains are composed of Gau ssian units which interact through a 6-12 Lennard-Jones potential. Fro m this study, the theta state for this model has been characterized. S caling curves have been obtained and different universal exponents, su ch as the theta point exponent upsilon, upsilon(theta), and the cross- over exponent Phi(t) have been numerically evaluated. The results are compared with theoretical predictions and with the values correspondin g to simulations in lattice models. The results for upsilon and upsilo n(theta) agree with the theory, but our best estimation for the cross- over exponent is closer to the simple mean field estimation.