A New Method to Describe the Multimode Jahn–Teller Effect Using Density Functional Theory

Abstract

A new method for the analysis of the adiabatic potential energy surfacesof Jahn–Teller (JT) active molecules is presented. It is based on the analogy betweenthe JT distortion and reaction coordinates. Within the harmonic approximation theJT distortion can be analysed as the linear combination of all totally symmetricnormal modes in the low symmetry minimum energy conformation. Contributionof the normal modes to the distortion, their energy contribution to the JT stabilisationenergy, the forces at high symmetry cusp and detailed distortion path canbe estimated quantitatively. This approach gives direct insight into the coupling ofelectronic structure and nuclear displacements. Further more, it is reviewed howmultideterminental DFT can be applied for the calculation of the JT parameters. Asexamples the results for VCl4, cyclopentadienyl radical and cobaltocene are given.