Density Functional Theory Study of the Multimode Jahn-Teller Effect – Ground State Distortion of Benzene Cation

Abstract

The multideterminental-DFT approach performed to analyze Jahn-Teller (JT) active molecules is described. Extension of this method for the analysis of the adiabatic potential energy surfaces and the multimode JT effect is presented. Conceptually a simple model, based on the analogy between the JT distortion and reaction coordinates gives further information about microscopic origin of the JT effect. Within the harmonic approximation the JT distortion can be expressed as a linear combination of all totally symmetric normal modes in the low symmetry minimum energy conformation, which allows calculating the Intrinsic Distortion Path, IDP, exactly from the high symmetry nuclear configuration to the low symmetry energy minimum. It is possible to quantify the contribution of different normal modes to the distortion, their energy contribution to the total stabilization energy and how their contribution changes along the IDP. It is noteworthy that the results obtained by both multideterminental-DFT and IDP methods for different classes of JT active molecules are consistent and in agreement with available theoretical and experimental values. As an example, detailed description of the ground state distortion of benzene cation is given. M. Zlatar ( )

Nuclear tunneling and dynamical Jahn-Teller effect in graphene with vacancy

“…For instance, there is also a pair of modes in the second shell 26 and so on. It is difficult to treat the JT problem when multiple vibrational modes are present (the so-called multimode problem [27][28][29] ) and often the single-mode approximation is made. 18,19 In the present case, due to the localized nature of the JT-active states (dangling sp 2 bond orbitals on the first shell atoms), the JT coupling to modes be-longing to further neighbor shells is expected to be quite weak.…”

Jahn–Teller and Pseudo-Jahn–Teller Effects: From Particular Features to General Tools in Exploring Molecular and Solid State Properties

“…This section is to introduce the JTE and PJTE (jointly, vibronic effects) in a (somewhat pedagogical) manner (using simple cases as examples), which allow us to demonstrate the main origins of these effects and their most important features that contribute to the observable phenomena in mater, emphasizing the latest achievements. In so doing, as mentioned above, we avoid bulk mathematical deduction for the more complicated cases, which can be find in the cited publications, ,,− ,− …”

“…The theoretical background of all these effects in atomic systems emerges from the first-principles as a delicate addition to the coupling between the electronic states and nuclear displacements, which occurs beyond the adiabatic approximation (vibronic coupling). The theory of the JTE and PJTE with many of their manifestations in molecular and solid state properties are rather well studied and continues developing. − Less attention has been paid so far to the PJTE, especially to its use as a tool in the study of the structure and properties of polyatomic syst...…”

“…As in any theoretical work, mathematical proofs of the origin of the JTE and PJTE structural instabilities based on first-principles are most important, but in detail they are of primary interest to more specialized readers and deserve separate consideration. For the more significant achievements in this field, see refs , , , and − for books; refs , , , and − for major reviews; refs − for JTE conference proceedings; and refs − …”

Density functional theory study of the multimode Jahn‐Teller problem in the fullerene anion

“…[23][24][25][26][27][28][29] In short, it is necessary to know the geometries and the energies of the HS and LS nuclear configuration. For the case of the LS conformation, since the system is in a nondegenerate electronic ground state, the geometry, as well as the corresponding energy, is obtained by standard DFT, whereas for the HS conformation the electronic state must be represented by more than one Slater Determinant, in this case by three.…”