Microstructure and self-diffusion coefficient of supercritical water by molecular dynamics simulation

By using molecular dynamics simulation with COMPASS force field,microstructure and self-diffusion coefficient of supercritical water were researched.The results show that the effect of the hydrogen bond on supercritical water is weakened obviously,and still exist.The bond length and the bond angle of the water molecular changed rapidly in the region of 648~748 K.The bond length and the bond angle of the water molecular changed slowly in 748~973 K.The characteristic peaks of radial distribution function increased with the increase of temperature in the region of 648~748 K,and decreased with the increase of temperature in the region of 748~973 K,which indicated that short range structure orderliness of water was changing with the increase of temperature.The self-diffusion coefficients of supercritical water were two orders of magnitude higher than ambient water,and increased with the increase of temperature,decreased with the increase of pressure.