MOLECULAR-DYNAMICS SIMULATION OF LIQUID WATER AT 523-K

Liquid water at 523 K is simulated assuming a flexible single-point-ch arged (SPC) potential. Both structural and dynamical properties at thi s temperature are compared with those at 298 K. The resulting structur e and self-diffusion coefficient are in satisfactory agreement with th e experimental data. The frequency peaks in the spectral densities are also in accord with the experimental infrared spectra. It has been sh own that the changes of the properties are related to the degree of hy drogen bonding. When the temperature increases from 298 K to 523 K man y hydrogen bonds vanish (40%) and the number of oxygen atoms with two or more direct hydrogen bonds is dramatically reduced (70%). Thus, the tridimensional hydrogen bond network, which is typical of liquid wate r at room and lower temperatures, is substantially destroyed at 523 K.