MOLECULAR-DYNAMICS SIMULATION WITH ATOMIC PARTIAL CHARGES UPDATE OF ERYTHROL IN WATER

A series of molecular dynamics simulations of erythrol in water was ca rried out with the purpose of analysing the influence of a change in m olecular conformation on atomic partial charge and its consequences on the simulation. Three cases were considered: one in which the charge was kept constant, as is regularly done; in the other two cases the ch arge was updated every 1000 and every 100 steps, respectively. Charges were recalculated by a quantum-mechanical semiempirical method and co nverged to a stable value in a relatively short simulation time. The r esults are analysed in terms of conformation, atom-water oxygen radial distribution functions, and hydrogen-bonding network. Some properties are almost independent of the charge assignment but others show a dis tinct behaviour depending on whether the charges remain fixed or are u pdated. No significant differences were observed with respect to updat e frequency. (C) 1998 Elsevier Science B.V.