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- Title
The Pseudo Jahn–Teller effect and NBO analysis for untangling the symmetry breaking in the planar configurations of M<sub>2</sub>X<sub>4</sub><sup>+</sup> (M = Si, Ge and X = Cl, Br, I): effect on electronic structure and chemical properties
- Authors
Kouchakzadeh, Ghazaleh; Mahmoudzadeh, Golrokh
- Abstract
Context: The Pseudo Jahn- Teller effect is a significant tool for evaluating molecular distortion and symmetry breaking. The PJT effect associated with NBO analysis can be a powerful method for studying the structural properties variations arising from D2h → C2h distortions. The theoretical studies on Si2X4+ and Ge2X4+ radical cations have been rare. The calculations have shown that C2h non-planar structures are more stable than planar structures with D2h symmetry. The (B 3 u + B 1 u) ⊗ b 2 g PJTE problem of M2X4+ compounds is a result of the coupling between the ground B3u state and the exited B1u state in the Qb2g direction causes. Also, the difference in M and X atoms can affect the PJT instability of compounds. The findings of this work show that the energy gap between the ground and excited states that have D2h symmetry decreases from M2Cl4+ to M2I4+ and increases from Si2X4+ to Ge2X4+. In fact, there is a significant relationship between instability of high-symmetry configurations, geometric parameters, electron delocalization, chemical hardness, electronegativity, electrophilicity index, and PJT stabilization energies. These results may serve to evaluate the distortion of similar systems. Methods: The structures of Si2X4+ and Ge2X4+ are optimized by LC˗BLYP, M06˗2X, and B3LYP methods with def2˗TZVPP basis set in GAMESS software. The details of the excited states of compounds are studied by the TD-DFT method. NBO analysis for planar and non˗planar structures is carried out at B3LYP/def2˗TZVPP level by the NBO 5. G program that demonstrates HOMO, LUMO, ED, bonding and antibonding orbital occupancies, bond order, and E2.
- Subjects
JAHN-Teller effect; CHEMICAL properties; CHEMICAL structure; SYMMETRY breaking; POLAR effects (Chemistry); ELECTRONIC structure; SILICON alloys
- Publication
Journal of Molecular Modeling, 2024, Vol 30, Issue 1, p1
- ISSN
1610-2940
- Publication type
Article
- DOI
10.1007/s00894-023-05792-1