COMPUTER-SIMULATION STUDY OF THE THETA-POINT IN 3 DIMENSIONS .1. SELF-AVOIDING WALKS ON A SIMPLE CUBIC LATTICE

Using the scanning simulation method we study the tricritical behavior at the Flory θ-point of self-avoiding walks (SAWs) of N≤250 steps with nearest neighbors attractions ε (e<0) on a simple cubic lattice (in the following paper we investigate tricritical trails on the same lattice). The tricritical temperature Tt is - ε/kBTt = 0.274±0.006 (one standard deviation). The results for the radius of gyration G and the end-to-end distance R are consistent with the theoretical prediction νt = 0.5 and with a logarithmic correction to scaling; the ratio 〈G2〉/〈R2〉 = 0.1659±0.0001 (calculated without taking into account correction to scaling) is only slightly smaller than the theoretical asymptotic value 1/6 = 0.1666.... The results for the partition function Z at Tt lead to γt = 1.005±0.017 in accord with theory and to μt = 5.058±0.014, where μt is the growth parameter; the correction to scaling in Z is found to be relatively small. For the chain length studied the divergence of the specific heat at T t(αt≃0.3) is significantly larger than that predicted by theory, (ln N)3/11 (i.e. αt = 0). Also, at Tt our data are affected by strong correction to scaling and are thus not consistent with the theoretical value of the crossover exponent φt = 0.5. © 1990 American Institute of Physics.