%0 Journal Article %T Quantum chemical study of the Jahn – Teller effect on the distortions of XO2 (X = O, S, Se, Te) systems %J Eurasian Chemical Communications %I Sami Publishing Company (SPC) %Z 2717-0535 %A Esmaeili, Ali %A Fazaeli, Reza %A Mohammadi Nasab, Esmat %D 2020 %\ 07/01/2020 %V 2 %N 7 %P 739-749 %! Quantum chemical study of the Jahn – Teller effect on the distortions of XO2 (X = O, S, Se, Te) systems %K the Jahn-Teller effect %K vibronic interactions %K Ab initio %K Quantum %K symmetry breaking %R 10.33945/SAMI/ECC.2020.7.1 %X Preliminary researches provided essential information about the optimized configuration of triatomic XO2 (X = O, S, Se, Te) systems, which were bent in the ground state and linear in their first excited state. The Jahn-Teller effects including the Jahn-Teller (JTE), the Renner-Teller effect (RTE), and the pseudo Jahn–Teller effect (PJTE) are parts of the most important reasons for structural distortion in the high symmetry configurations for each molecular system. This study purpose was to investigate the dependence between PJT parameters including the vibronic coupling constant values ​​(F), energy gap between reference states (Δ), and initial force constant (K0). In all above mentioned molecules, stability were increased with the reduction in the symmetry level. This increment was attributed to the PJTE. The vibronic coupling interaction between the ground (Σg), and the first excited states (Πu) through the PJTE problem (PJT (Σg+ Πu) × Πu) was because of the asymmetry and molecules bending phenomenon. The hardness difference parameter Δ[η (C2V) -η (D∞h)] decreases from O to Te (30.42, 22.66, 22.65, 22.58 Kcal/mol). These changes could explain the trend, which were observed for the D∞h  → C2V conversion process. %U https://www.echemcom.com/article_105457_f6f5e5d2a4f281a4bb58493e59b4cf08.pdf