ON THE USE OF THE GAUSSIAN CHAIN AS A MONTE-CARLO SIMULATION-MODEL FOR THE EQUILIBRIUM PROPERTIES OF POLYMER-SOLUTIONS

We have explored the performance of a simulation model for Gaussian ch ains at different concentrations in a good solvent. The Gaussian stati stics for the distances between contiguous beads in the model is direc tly implemented in the individual moves of a Monte Carlo algorithm. Wh en the results of conformational properties for the Gaussian model are compared with those provided by a freely jointed model in the same co nditions, significant differences arise at finite concentrations. The modeled Gaussian chain yields incorrect results for the quadratic aver age dimensions [R(2)] and [S-2] at high concentrations, but correctly reproduces the results for the scaled end-to-end distance distribution function at any concentration, showing the effects of the screening o f excluded volume when concentration increases. The reason for the wro ng behavior of the simulated Gaussian model comes from a strong distor tion of the ''bond distance'' distribution as a result of the concentr ation increase. We conclude that this model can only be safely applied to infinitely dilute solutions.