Structures of high-density and low-density water

The three sire-sire partial structure factors for water have been measured as a function of pressure, using neutron diffraction, at a temperature of 2 68 K. It is found that the measured structure functions imply a continuous transformation with increasing pressure from a low-density form of water (r ho(L) similar to 0.0295 molecules/Angstrom(3)), with an open, hydrogen-bond ed tetrahedral structure, to a high-density form of water (rho(H) similar t o 0.0402 molecules/Angstrom(3)), with nontetrahedral O-O-O angles and a col lapsed second coordination shell, which implies broken hydrogen bonds betwe en the first and second coordination shells.