A decomposition scheme for the partitioning of normal-coordinate vibrational frequencies into individual internal-coordinate "intrinsic~ frequencies is presented. This scheme assigns to each internal coordinate a frequency that is representative of a vibration described solely by motion of that particular coordinate. This facilitates the interpretation of harmonic vibrational frequencies and their associated normal-coordinate displacements, especially in those cases where the normal coordinates are best described by the coupling of several internal coordinates. The utility of the method is demonstrated via application to several simple hydrides and cycloalkanes, using ab initio SCF molecular structures and Cartesian force constant matrices.
Available at: http://works.bepress.com/mark_gordon/78/