MOLECULAR-DYNAMICS SIMULATION OF SURFACE-TENSION FOR POLAR-MOLECULES - CORRECTION FOR LONG-RANGE INTERACTION BY GENERALIZED VAN-DER-WAALS THEORY

A new method, based on the Generalized van der Waals (GvdW) theory, fo r the correction of interaction truncation errors in the calculation o f surface tensions from molecular dynamics simulations of polar liquid s is presented and applied to SPC water. Several simulations using tru ncation radii ranging from 0.9 to 1.6 nm of a 4 nm thick SPC water sla b are reported. The surface tension as obtained directly from the simu lations grows with the cutoff from 56 to 80 mN m(-1), whereas the corr ection ranges from 24 to 8 mN m(-1), yielding resulting surface tensio ns between 74 and 88 mN m(-1) with a minimum at a truncation radius of 1.2 nm. The minimum might reflect the shell structure in the liquid a nd the deviation from an ideal dipole (assumed in the GvdW calculation ) for the SPC model.