Combined inelastic neutron scattering and solid-state density functional theory study of dynamics of hydrogen atoms in muscovite 2M1

Abstract

Inelastic neutron scattering (INS) was used to study dynamics of the hydrogen atoms in natural 2M1 muscovite in the 150–1200 cm–1 energy range. The resultant INS spectra are interpreted by means of solid-state density functional theory calculations covering both normal mode analysis and molecular dynamics. While signatures of the Al-O-H bending modes were found over the whole energy transfer range, the dominant contributions were observed between 800–1000 cm–1. The modes assigned to the in-plane movements of the respective hydrogen atoms are well defined and always appear at high energies. In contrast, the modes corresponding to the out-of-plane movements are spread over large energy transfer ranges, extending down to the region of external (lattice) modes. The positions of the high-energy modes contributing to the INS band at ~907 cm–1 depend on the distance of respective hydrogen atoms to the nearest oxygen atom of the basal net and its polarity.