MOLECULAR-DYNAMICS SIMULATION OF LIQUID WATER AT 523-K

Liquid water at 523 K is simulated assuming a flexible single-point-charged (SPC) potential. Both structural and dynamical properties at this temperature are compared with those at 298 K. The resulting structure and self-diffusion coefficient are in satisfactory agreement with the experimental data. The frequency peaks in the spectral densities are also in accord with the experimental infrared spectra. It has been shown that the changes of the properties are related to the degree of hydrogen bonding. When the temperature increases from 298 K to 523 K many 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 water at room and lower temperatures, is substantially destroyed at 523 K.