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On the UV spectroscopy and photodynamics of octatetraene.
- Source :
-
Molecular Physics . Jun2023, Vol. 121 Issue 11/12, p1-11. 11p. - Publication Year :
- 2023
-
Abstract
- The UV absorption spectrum of all-trans-octatetraene is reinvestigated theoretically, focussing on the strongly dipole-allowed 1 A g – 1 B u transition. The dynamical calculations rely on ab initio multistate CASPT2 (MS-CASPT2) computations of the underlying potential energy surfaces and coupling elements, and the multiconfiguration time-dependent Hartree (MCTDH) method for solving the time-dependent Schrödinger equation for the nuclear motion. The vibronic structure of the absorption band near 2700 Å is well reproduced, better than ever before by a purely ab initio approach. The C–C single bond and C = C double bond stretching modes dominate the vibrational structure of the transition. While the latter resembles nearly harmonic motion on weakly coupled potential energy surfaces, the time-dependent calculations reveal a subpicosecond electronic population transfer from the 1 B u state to the lower-lying 2 A g state proceeding on a time scale of ∼ 50 fs . The details of this internal conversion process and its relation to the conical intersection between the two excited states are discussed, paying particular attention to the impact of the 1 B u – 2 A g energy gap on the dynamics. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00268976
- Volume :
- 121
- Issue :
- 11/12
- Database :
- Academic Search Index
- Journal :
- Molecular Physics
- Publication Type :
- Academic Journal
- Accession number :
- 165049806
- Full Text :
- https://doi.org/10.1080/00268976.2022.2132186