In order to investigate further the nature of the disorder observed in Form I at high temperature, a series of unit-cells were created to represent the type of disorder that may be found. X-ray crystallography and neutron scattering indicate that at room temperature about half of the S-H groups are involved with SH...S hydrogen bonds and about half with SH...O hydrogen bonds. These different environments may be dispersed randomly throughout the crystal or they may be localised in domains. reported previously. The hydrogen bonding patterns established at the outset of the calculations were maintained throughout the unconstrained optimisation procedure, indicating that there is a barrier for the relaxation of the S-H...O to the S-H...S hydrogen bonding pattern.