Table 1 Number of water molecules per unit cell (Zcell), equilibrium volume of unit cell (Vcell), average distance between oxygen atoms in adjacent water molecules (dO-O), mass density (ρ), and lattice cohesive energy per water molecule (Elatt) for various ice and guest-free clathrate phases.

The values in parentheses are experimental data.

PhaseZcellVcell3)dO-O (Å)ρ (g/cm3)Elatt (kJ/mol)
Ice XI8266 (257*)2.785 (2.735*)0.900 (0.930*)62.84 (58.86)
Ice i82802.7850.85561.31
s-I4616922.7650.81361.38
s-K8029622.7650.80860.76
s-II1365059 (5022)2.765 (2.751)0.804 (0.81)61.37
s-T124532.7950.79260.23
s-H3413252.7850.76860.79
SGT6426502.7650.72259.27
s-III4824232.7650.59355.77

*Results of the study by Leadbetter et al. (12) obtained from neutron diffraction at 5 K.

†Results of the study by Whalley (34) with zero-point energy contributions removed.

‡Results of the study by Falenty et al. (11) obtained from neutron diffraction at 5 K.