A MODIFIED REAL PARTICLE METHOD FOR THE CALCULATION OF THE CHEMICAL-POTENTIALS OF MOLECULAR-SYSTEMS

We propose a new technique, which is a combination of the test and real particle methods proposed originally by Widom, for the calculation of the chemical potentials of molecular systems from computer simulation. The technique involves the creation of a hole in the fluid by removing a particle from the simulated system, and subsequently reinserting it as a test bead. The equations for the calculation of chemical potentials are derived, and it is shown that the results obtained by this method for Lennard-Jones fluids are accurate over larger ranges in temperature and density than other traditional methods. In spite of these advantages for simple systems, the proposed technique is expected to be of greatest value when dealing with complex systems containing ionic or polymeric molecules.