title: Sampling microcanonical ensembles of trajectories using harmonic approximation in internal coordinates.
abstract: In this paper, we modify quasiclassical harmonic sampling of microcanonical ensembles of trajectories by using the curvilinear internal coordinates. The harmonic approximation in the curvilinear normal coordinates provides a more realistic description of the PES than in the conventional rectilinear ones at finite displacements. Therefore, the sampling of vibrations in the internal coordinates significantly improves the quality of the sampling in a block-box fashion, providing more realistic displacements and reducing the errors in the potential energy. In particular, the sampling of large-amplitude torsion vibrations, which is non-realistic in the Cartesian modes, becomes accurate or acceptable in the curvilinear modes.
authors.affiliation: G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Akademicheskaya St. 1, Ivanovo 153045, Russia.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Rybkin
authors.affiliation: Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033, N-0315 Oslo, Norway.
authors.forename: Ulf
authors.initials: U
authors.lastname: Ekström