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 surfaces of Jahn-Teller (JT) active molecules is presented. It is based on the analogy between the JT distortion and reaction coordinates. Within the harmonic approximation the JT distortion can be analysed as the linear combination of all totally symmetric normal modes in the low symmetry minimum energy conformation. Contribution of the normal modes to the distortion, their energy contribution to the JT stabilisation energy, the forces at high symmetry cusp and detailed distortion path can be estimated quantitatively. This approach gives direct insight into the coupling of electronic structure and nuclear displacements. Further more, it is reviewed how multideterminental DFT can be applied for the calculation of the JT parameters. As examples the results for VCl 4 , cyclopentadienyl radical and cobaltocene are given.

Multimode Jahn-Teller effect in bulk systems: A case of the NV0 center in diamond

“…This atomic configuration is not a stationary point on the potential energy surface, and there is coupling between the E electronic states with the non-totally-symmetric e vibrations. Therefore, our procedure for calculating the JT parameters consists of the following steps [30]: (i) a geometry optimization of the NV 0 center in a high C 3v symmetry with an occupation of 0.5 on both e orbitals, (e x ) 0.5 (e y ) 0.5 ; (ii) energy calculation using the highsymmetry geometry (G HS ) obtained by step (i) and with the same electronic configuration as that in the lower-symmetry structure. This is achieved by performing a calculation with an integer occupation on one of the doubly degenerate orbitals, e.g., (e x ) 1 (e y ) 0 ; (iii) a complete geometry optimization on the lower-symmetry structure, with the same electron occupancy as in step (ii).…”

“…The contribution of all the totally symmetric modes to the distortion and their changes along the IDP can also be distinguished. Details about this method have been represented in previous work [23,30].…”

Density functional theory study of the Jahn-Teller effect in cobaltocene

“…This is the essence of our proposition how to treat the multimode problem. More details about this approach will be published shortly [49]. (15) The set of normal modes q = (q 1 , q 2 , …, q n ), n being the number of the totally symmetric vibrations in low symmetry, are orthonormal, that is, q i ؒ q j = δ ij : (16) (17) In order to be consistent with the usual treatments [2] and the previous qualitative arguments, we correlate the vibrations in the minimum-energy conformation of low symmetry to the ones in high symmetry by the method developed by Hug et al [44,45], using overlap and similarities of the massweighted Cartesian displacements of the two different configurations.…”

DFT study of the Jahn–Teller effect in Cu(II) chelate complexes

“…Path from the HS to the LS minimum obtained in this way is the Intrinsic Distortion Path (IDP), which gives additional information about the microscopic origin and mechanism of the distortion. Details about this approach has been described in our previous papers [4,14].…”

“…Further motivation for this work comes from our continuous interest in systems where the JT distortion arises as a consequence of coupling of the electronic states with a number of different normal modes, so called multimode JT problem. Thus, in addition we performed the analysis of the multimode JT effect on the above mentioned systems using the method recently proposed by us [4,14].…”