CALCULATION AND COMPARISON OF ALPHA-VIBRONIC, EPSILON-VIBRONIC AND TAU-VIBRONIC COUPLING-CONSTANTS OF OCTAHEDRAL COORDINATED D-ELECTRON SYSTEMS - CRCL63- AS EXAMPLE

t X (alpha + epsilon + tau)-coupling constants of octahedral transitio n metal complexes are calculated within an electrostatic model. The el ectron-ligand interaction is taken into account by expanding the poten tial energy V-eL into spherical harmonics and differentiating it with respect to the vibrational symmetry coordinates of the molecule. In fi rst order matrix elements of the form [psi(d)\partial derivative V/par tial derivative Q\ psi(d)] are calculated from which coupling constant s, stabilization energies and Huang-Rhys factors are computed. The T-4 (2g) electronic state of [CrCl6](3-) is characterized as mainly distor ted along the totally symmetric and the e(g)-coordinates. Nearly quant itative agreement with results deduced from luminescence spectra is ac hieved.