Fig. 7: Schematic representation of potential energy hypersurfaces of Jahn–Teller distorted states.
From: Accurate and convergent energetics of color centers by wavefunction theory
The plots illustrate the vicinity of the minimum-energy crossing point (MECPs) between \({(1)}^{3}\bar{E}\) states (a) and \({(1)}^{1}\bar{E}\) states (b). The relative energy levels of \({\bar{A}}^{{\prime} }\), \({\bar{A}}^{{\prime\prime} }\) and MECP structures were calculated at SS-CASSCF(6e,4o)-NEVPT2 level. Jahn–Teller parameters (EJT, δJT) were obtained from energy differences, as shown. Parameter hνe was calculated as an effective phonon energy between \({\bar{A}}^{\prime}\) and \({\bar{A}}^{\prime\prime}\) minima, using a 50–50% weighing for the two degenerate \(\bar{E}\) states. In the structure plots, the carbon atoms neighboring the vacancy are presented, N-V axis is out of plane.
