Molecular dynamics simulation of inelastic neutron scattering spectra of librational modes of water molecules in a layered aluminophosphate

Abstract

Molecular dynamics (MD) is well established as a method for computing static and dynamical properties of solids. In this work we present a comparison of the experimental and calculated structures and vibrational spectra calculated using MD and the experimental spectrum from inelastic neutron scattering of a templated and hydrated layered aluminophosphate. We discuss the water librational modes between 300-800 cm−1 where the assignment of peaks in the experimental spectrum is not clear. We have identified the librational modes from the trajectories of the water molecules. The various librational modes were decomposed into their components about the main rotational axis of the water molecules, and the different weight of each libration in the final spectrum was thereby established. From this analysis we were able to correlate three librational modes with water molecules in three different environments.