An integral equation study of a simple point charge model of water

We present an extensive integral equation study of a simple point charge mo del of water for a variety of thermodynamic states ranging from the vapor p hase to the undercooled liquid. The calculations are carried out in the mol ecular reference-hypernetted chain approximation and the results are compar ed with extensive molecular dynamics simulations. Use of a hard sphere flui d as a reference system to provide the input reference bridge function lead s to relatively good thermodynamics. However, at low temperatures the compu ted microscopic structure shows deficiencies that probably stem from the la ck of orientational dependence in this bridge function. This is in marked c ontrast with results previously obtained for systems that, although similar ly composed of angular triatomic molecules, do not tend to the tetrahedral coordinations that are characteristic of water. (C) 1999 American Institute of Physics. [S0021-9606(99)52202-2].