The Jahn-Teller effect in the triply degenerate electronic state of methane radical cation

2011 ◽  
Vol 135 (17) ◽  
pp. 174304 ◽  
Author(s):  
T. Mondal ◽  
A. J. C. Varandas
Keyword(s):  
Electronic State ◽  
Radical Cation ◽  
Teller Effect ◽  
Jahn Teller ◽  
Jahn Teller Effect

Description of Bond Pseudorotation, Bond Pseudolibration, and Ring Pseudoinversion Processes Caused by the Pseudo-Jahn–Teller Effect: Fluoro Derivatives of the Cyclopropane Radical Cation

2014 ◽  
Vol 67 (3) ◽  
pp. 435 ◽  
Author(s):  
Wenli Zou ◽  
Dieter Cremer
Keyword(s):  
Radical Cation ◽  
Positive Charge ◽  
Radical Cations ◽  
Molecular Geometry ◽  
Teller Effect ◽  
Curvilinear Coordinates ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Derivatives Of ◽  
Fluoro Derivatives

Curvilinear coordinates are used to describe the molecular geometry and the pseudo-Jahn–Teller surface of F-substituted cyclopropane radical cations using the equation-of-motion coupled cluster EOMIP-CCSD/cc-pVTZ approach. The monofluoro derivative 2 undergoes bond pseudolibration (incomplete bond pseudorotation) between two symmetry-equivalent biradicaloid forms separated by a barrier of 2.2 kcal mol–1 (1 kcal mol–1 = 4.186 kJ mol–1) at low temperature. Bond pseudorotation and ring pseudoinversion have barriers of 12.1 and 16.5 kcal mol–1 respectively. The relative energies of 2 are affected by the distribution of the positive charge in the C3 ring and the formation of a CF bond with partial π character. There is a change of the CF bond length from 1.285 to 1.338 Å along the bond pseudorotation path. The changes of the CF bond outweigh the deformation effects of the C3 ring; however, both are a result of the pseudo-Jahn–Teller effect according to an (A′ + A′′) ⊗ (a′ + a′′) interaction. For the pentafluoro derivative 3 of the cyclopropane radical cation, bond pseudorotation has a barrier of 16.3 kcal mol–1 whereas ring pseudoinversion is hindered by a barrier of 21.7 kcal mol–1. Radical cation 3 is the first example of a trimethylene radical cation.

Energy component analysis of the Jahn–Teller effect in the methane radical cation

1991 ◽  
Vol 94 (12) ◽  
pp. 8083-8088 ◽  
Author(s):  
Russell J. Boyd ◽  
Katherine Valenta Darvesh ◽  
Paul D. Fricker
Keyword(s):  
Radical Cation ◽  
Component Analysis ◽  
Teller Effect ◽  
Energy Component ◽  
Jahn Teller ◽  
Jahn Teller Effect

Studies of the Jahn-Teller effect .II. The dynamical problem

1958 ◽  
Vol 244 (1236) ◽  
pp. 1-16 ◽  
Keyword(s):  
Electronic State ◽  
Quantum Number ◽  
Vibrational Energy ◽  
Dynamical Problem ◽  
Oscillator Strengths ◽  
Teller Effect ◽  
Linear Molecule ◽  
Electronic Band ◽  
Jahn Teller ◽  
Jahn Teller Effect

This paper examines the vibronic energy levels of a symmetrical non-linear molecule in a spatially doubly degenerate electronic state which is split in first order by a doubly degenerate vibrational mode. The vibronic levels are classified by a quantum number, which in certain cases is formally related to the combined angular momentum of electronic and vibrational motion, and numerical values are obtained for the energies of these levels as functions of this quantum number and a dimensionless parameter measuring the magnitude of the electronic-vibrational coupling. It is shown that the selection rules for transitions from these vibronic levels to those of a non-degenerate electronic state allow changes in vibrational energy of any integral number of quanta, as though the Jahn-Teller effect were equivalent to a distortion which makes allowed vibrational transitions which would otherwise be forbidden. Numerical values are given for the oscillator strengths of vibronic absorption or emission bands involving transitions between a Jahn-Teller distorted state and an electronically non-degenerate state. It is found that in transitions from the latter to the former the vibrational structure of the electronic band exhibits two intensity maxima if the distortion is large.

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