title: Coarse Graining of Intermolecular Vibrations by a Karhunen-Loève Transformation of Atomic Displacement Vectors.
abstract: We have formulated a procedure for evaluating the anisotropic stiffness of a molecular assembly. First, we show how to reduce the dimensions of the matrices that appear in a conventional Hessian analysis of mass-weighted coordination by using a 12-dimensional transverse-rotational basis set for expansion. This treatment yields matrix representations of the intermolecular force and inertial load of the constituent molecules. Next we applied this procedure to 2-aminopyridine dimers and numerically analyzed the low-frequency (∼THz region) normal-mode vibrations. By validating the elements of stiffness matrix, this study exemplifies a derivation of the parameters necessary for the normal-mode analysis of a large system like a crystal, without any explicit representation of the potential functions.
authors.affiliation: Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Houjou