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https://www.ias.ac.in/article/fulltext/boms/043/0293

Symmetry descent phenomena; pseudo Jahn–Teller effect; Ab initio calculations; ground-excited states interactions.

Manifestation of descent symmetry phenomena induced by pseudo Jahn–Teller interactions is reported for the P$_4$ dicationic tetrahedral structure and its As$_4$ and Sb$_4$ analogues. The symmetry descent phenomena in the dicationic tetrahedral structure for the series is caused by the pseudo Jahn–Teller effect (PJTE) where the unstable (high T$_{\rm d}$ symmetry) configuration distorts to the equilibrium geometry with a lower, C$_2$ symmetry. State averaging six low-lying electronic states via CASSCF(8,8)/cc-pVTZ–(PP) computations determined the adiabatic potential energy surfaces along the distorting normal coordinate. The (E$_{\rm (I)}$ $+$ A$_1$ $+$ E$_{\rm (II)}$) $\otimes$ $e$ for the M$_4^{2+}$ (M $=$ P, As, Sb) series has been formulated accordingly. Subsequently, the coupling constants were estimated by fitting energies obtained from the PJTE equations. Moreover, to understand how removing or adding electrons affects the PJTE in the M$_4^{2+}$ series, electronic configurations were analysed for M$_4^{(0,2+,4+)}$ analogues in which the M$_4^{(0,4+)}$ are stable in their tetrahedral structure.

ALI REZA ILKHANI^{1 2} WILLIAN HERMOSO³

1. Department of Chemistry, Yazd Branch, Islamic Azad University, Yazd, Iran
2. Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada
3. Department of Chemistry, Institute of Environmental, Chemical and Pharmaceutical Sciences, Federal University of Sao Paulo, Sao Paulo, Brazil

Published

12 November 2020

Manuscript received

13 April 2020

Accepted

22 June 2020

Final version published online

12 November 2020