Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 49: Ab-initio approaches to excitations in condensed matter II
O 49.5: Vortrag
Donnerstag, 26. März 2009, 11:30–11:45, SCH 251
Time-dependent density functional study of S1 ← S0 transition of 2,3-benzofluorene — •Davoud Pouladsaz1, Gael Rouillé2, Friedrich Huisken2, Michael Schreiber1, and Reinhard Scholz3 — 1Institut für Physik, Technische Universität Chemnitz — 2Labor Astrophysik, Friedrich-Schiller-Universität Jena — 3Walter Schottky Institut, Technische Universität München
We have recently studied the S1(1A′) ← S0(1A′) absorption spectrum of 2,3-benzofluorene (Bzf) [1]; the potential energy surfaces of the Sn=0,1,2 states of Bzf have been investigated with calculations based on the time-dependent density functional theory (TD-DFT). At the B3LYP/TZ level of theory, TD-DFT does not deliver a realistic difference between the excited S1 and S2 potential energy surfaces, a problem which can be avoided by introducing a reference geometry where this difference coincides with the observation. In this geometry, an expression for the Herzberg-Teller corrected intensities of the vibronic bands is proposed, allowing a straightforward assignment of the observed a′ modes below 900 cm−1, including realistic calculated intensities. For vibronic bands at higher energies, the agreement between calculated and observed modes is deteriorated by substantial Dushinsky rotations and nonparabolicities of the potential energy surface S1. We consider our calculations to be the best approach to an ab initio study realized for Bzf until now since only parametrized force fields had been used before.
[1] A. Staicu, G. Rouillé, Th. Henning, F. Huisken, D. Pouladsaz, and R. Scholz, J. Chem. Phys. 129, 074302 (2008)