title: Direct dynamics study of ultrafast vibrational energy relaxation in ice Ih.
abstract: Car-Parrinello molecular dynamics (CPMD) and a previously developed wave packet model are used to study ultrafast relaxation in water clusters. Water clusters of 15 water molecules are used to represent ice Ih. The relaxation is studied by exciting a symmetric or an asymmetric stretch mode of the central water molecule. The CPMD results suggest that relaxation occurs within 100 fs. This is in agreement with experimental work by Woutersen and Bakker and the earlier wave packet calculations. The CPMD results further indicate that the excitation energy is transferred both intramolecularly and intermolecularly on roughly the same time scale. The intramolecular energy transfer occurs predominantly between the symmetric and asymmetric modes while the bend mode is largely left unexcited on the short time scale studied here.
authors.affiliation: Department of Chemistry, Physical Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden.
authors.forename: Carina
authors.initials: C
authors.lastname: Bäcktorp
authors.forename: Jens Aage
authors.initials: JA
authors.lastname: Poulsen
authors.forename: Gunnar
authors.initials: G
authors.lastname: Nyman