Vibrational transition current density in (2S,3S)-oxirane-d2:: visualizing electronic and nuclear contributions to IR absorption. and vibrational circular dichroism intensities

Vibrational transition current density (TCD) plots and charge-weighted nuclear displacement vectors for selected vibrational modes of A and B symmetry in (2S,3S)-oxirane-d(2) are used to visualize the electronic and nuclear contributions to infrared absorption and vibrational circular dichroism intensities. Vibrational TCD provides a vector field map of the integrand of the electronic contribution to the velocity-form electric dipole transition moment. Linear nuclear and electronic charge flow in planes parallel to the electric dipole transition moment vector provides visualization of contributions to IR intensity, while angular and circular charge flow perpendicular to this vector provide visualization of the magnetic dipole transition moment content of vibrational circular dichroism intensity. Four vibrational modes with several types of nuclear motion and the effect of basis set size on vibrational TCD are examined. (C) 2000 Elsevier Science B.V. All rights reserved.