Novel Effect Induced by Pseudo-Jahn鈥揟eller Interactions: Broken Cylindrical Symmetry in Linear Molecules
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- 作者：Willian Hermoso ; Yang Liu ; Isaac B. Bersuker
- 刊名：Journal of Chemical Theory and Computation
- 出版年：2014
- 出版时间：October 14, 2014
- 年：2014
- 卷：10
- 期：10
- 页码：4377-4388
- 全文大小：597K
- ISSN：1549-9626
文摘
It is shown that in linear molecules the pseudo-Jahn鈥揟eller (PJT) interaction of a 危 or 螤 term with a 螖 term induces a bending instability that is angular dependent, reducing the symmetry of the adiabatic potential energy surface from expected D鈭瀐 to D4h and C鈭瀡 to C2v or C4v. This spontaneously broken cylindrical symmetry (BCS) emerges from the solution of the vibronic coupling equations of the PJT effect (PJTE) problems (危+螖)鈯梬, (螤+螖)鈯梬, (螤+危+螖)鈯梬, and (螖+螖)鈯梬, where w includes linear, quadratic, and fourth order vibronic coupling terms, and it is confirmed by ab initio calculations for a series of triatomic molecules with ground or excited 螖 terms. The BCS is due to the angular symmetry of the electronic wave functions of the 螖 term, 鈭糲os 2蠁, and 鈭約in 2蠁, split by the fourth order vibronic coupling, which in overlap with the other symmetry wave functions of the 危 or 螤 term provides for the periodical symmetry of the added covalency that facilitates the bending. The mechanism of this PJT-induced BCS effect is discussed in detail; the numerical values of the vibronic coupling parameters for the molecules under consideration were estimated by means of combining separate ab initio calculations of some of them with a procedure fitting the analytical expressions to ab initio calculated energy profiles. It is also shown that the bending of linear molecules in 螖 states, similar to 螤 states, is exclusively a PJT (not Renner鈥揟eller) effect. The BCS revealed in this paper illustrates again the predicting power of the PJTE.