A SIMPLE TEST FOR EVALUATING THE TRUNCATION EFFECTS IN SIMULATIONS OF SYSTEMS INVOLVING CHARGED GROUPS

We report the results from a molecular dynamics (MD) simulation on a 1.0 M aqueous NaCl solution using the classical SPC water model and a treatment of long-range electrostatic forces involving a 9-16 Angstrom twin-range cut-off. This study was undertaken to explore the importance of truncation effects in simulations involving charged species which employ cut-offs at longer range than typically used in MD. Artefacts were discerned in the ion-ion radial distribution functions at approximate to 16 Angstrom, indicating that increasing the length scale of the truncation scheme does not necessarily lead to reliable trajectories. Our results indicate that 'charge group-charge group' radial distribution functions are a sensitive test for the detection of artefacts due to truncation and it is suggested that they should be used as a routine screening device in the analysis of MD systems involving charged groups.