Equilibrium molecular dynamics calculation of the bulk viscosity of liquidwater

Twenty independent equilibrium molecular dynamics simulations were performe d in NVE ensemble to calculate the bulk viscosity of water at a temperature of 303 K and a density of 0.999 g cm(3). The energy of each simulation wit h a production time of 200 ps was conserved within 1 part in 10(4). By stop ping the velocity-scaling procedure at a proper step, the energies of indep endent simulations were specified precisely. This caused the simulations of different start configurations to sample the same NVE ensemble. The shear viscosity of SPC/E water obtained in the present study was 6.5 +/- 0.4 x 10 (4) Pa s, which is in close agreement with a previous calculation in the NV T ensemble (Balasubramanian, S., Mundy, C. J., and Klein, M. L., 1996, J. c hem. Phys., 105, 11 190). The bulk viscosity was 15.5 +/- 1.6 x 10(4) Pa s, which is 27% smaller than the experimental value. Thus, like its behaviour in predicting the shear viscosity, the SPC/E model also underestimates the bulk viscosity of real water.