A very efficient strategy to evaluate the "free volume" and the "unoccupied volume" in polymer matrices is proposed. The method, which has been denoted EVEBAT (Empty Volume Evaluation Based on Atom-Types), emerges from the concept of atom type, which is the basis of a force field. Accordingly, the numerical treatment is minimized by analyzing the atom types used to describe the polymer matrix, which are always a few, rather than all the explicit, atoms involved in it. The performance of the new method has been pointed out by a detailed comparison with the classical insertion algorithms. (C) 2003 Wiley Periodicals, Inc.
