FLEXIBLE MOLECULE RMC MODELLING APPLIED TO ICE IH
M.N. Beverley
School of Physical Sciences, University of Kent, Canterbury, Kent, CT2 7NR.
Keywords: diffuse scattering, reverse Monte Carlo, ice Ih
The analysis of neutron single crystal diffuse scattering enables one to obtain information concerning structural disorder. This disorder is a result of deviations, static and thermal, from the long range order. In ice-Ih at low temperatures, the hydrogen disorder is primarily reflected in the diffuse scattering.
Attempts were made to extract information on structural disorder from ice-Ih diffuse scattering using a specially developed reverse Monte Carlo method, RMCX [1]. The results obtained were inconsistent with those from accepted techniques. Further attempts, [2] using an extension of the RMCX technique, RMCXMOLS, allowed the molecule to remain rigid during modelling, such that certain bond lengths and bond angles were constrained. It was found that the results were highly dependent upon the initial intra-molecular geometry.
This poster reports initial results of a further extension of RMCX, in which the molecule is moved as a single entity but the atomic positions within it are also allowed to relax during modelling.