Analysis of librational modes of ice XI studied by Car-Parrinello molecular dynamics

- Theoretical IR spectra of ice XI were calculated by ab initio CP molecular dynamics.
- The assignment of modes was done by analysis of power and polarization spectra.
- The results were compared with experimental and other theoretical spectra of ice XI.
- Our simulations can be used for investigation of existence of ice XI in space.

Theoretical infrared spectra of ice XI at 4 and 40 K were obtained by Car-Parrinello molecular dynamics calculations and evaluating the dipole moment using maximally-localized Wannier functions. In order to improve the agreement between theoretical and experimental spectra, the Kramers-Kronig relations were applied. Based on analysis of power and polarization spectra the assignment of modes was carried out. The results were compared with experimental and theoretical spectra of ice XI, performed by other authors. Such simulations can be very useful while investigating the existence of ice XI in space.