Monte Carlo studies of the aqueous hydration of cis and trans N-methyl-acetamide: sensitivity of results to convergence and to choice of intermolecular potential functions Abstract: A series of liquid state Monte Carlo computer simulaitions in the N-methyl acetamide in water (NMA molecule) are described, considering both the cis and trans isomeric froms of NMA. Two independent sets of calculations were performed, one based on the potential functions developed by Clementi and coworkers (CPF) used in conjunction withe the Matsuoka et al. (MCY) water-water potential and the other set using the OPLS potential of Jorgensen and coworkers for the solute-water interactions and the TIP4P potential for the water-water interactions. The relative hydration energies of the cis and trans isomers of NMA and the transfer energies of NMA from free space to water are discussed with respect to the convergence level of the simulations and the sensitivity of results to the choice of intermolecular potential functions. The structural chemistry of aqueous hydration for NMA is developed from the simulation result based on Proximity Analysis. The sensitivity of structural and energetic indices of analysis to choice of potential is described. Preliminary results of the calculation of the hydration contribution to the free energy are also presented.