Vibronic Coupling Density Analyses for Molecular Deformation

Abstract

The basis of the vibronic coupling density (VCD) analysis has been introduced in Chap. 2. The vibronic coupling constant (VCC) as well as the VCD will be exactly defined in Sect. 5.4.1. As seen in Sect. 5.4.1, both are starting from the ab initio molecular Hamiltonian, and systematic, rational ways to understand chemical phenomena, and which can give the quantitative evaluation of the force applied under the chemical deformation process. We offer the approach of chemistry with more rational and general way through the visualization by VCD and the evaluation by VCC. Vibronic coupling is the interaction between vibrational and electronic motions. The local picture of a vibronic coupling can be expressed in terms of electronic and vibrational structures using VCD. We describe the concepts of VCC and VCD within the crude adiabatic approximation.KeywordsVibronic coupling densityVibronic coupling constantElongationOrbital relaxationRenner–Teller effectPseudo-Jahn–Teller effectOrbital vibronic coupling densityOrbital overlapPotential derivativeImaginary modeQuadratic vibronic coupling densityJahn–Teller effectEffective vibronic coupling densityRegioselectivityStructural relaxation