THE DOMINANT ONE-PHOTON-EXCITED AND 2-PHOTON-EXCITED STATES IN THE NONLINEAR-OPTICAL RESPONSE OF OCTATETRAENE - AB-INITIO VERSUS SEMIEMPIRICAL THEORETICAL DESCRIPTIONS

Citation
D. Beljonne et al., THE DOMINANT ONE-PHOTON-EXCITED AND 2-PHOTON-EXCITED STATES IN THE NONLINEAR-OPTICAL RESPONSE OF OCTATETRAENE - AB-INITIO VERSUS SEMIEMPIRICAL THEORETICAL DESCRIPTIONS, Chemical physics letters, 279(1-2), 1997, pp. 1-8
Citations number
25
Categorie Soggetti
Physics, Atomic, Molecular & Chemical
Journal title
ISSN journal
00092614
Volume
279
Issue
1-2
Year of publication
1997
Pages
1 - 8
Database
ISI
SICI code
0009-2614(1997)279:1-2<1:TDOA2S>2.0.ZU;2-Y
Abstract
The one-and two-photon singlet excited states, relevant for the descri ption of the nonlinear optical response of the octatetraene molecule, have been characterized by the ab initio complete active space self-co nsistent-field/multiconfiguration second-order perturbation theory (CA SSCF/CASPT2) technique. We compare the nature of the main electronic c ouplings among excited states, as obtained at the ab initio level, to that provided by the semiempirical Pariser-Parr-Pople (PPP) method. Bo th approaches indicate the presence of a dominant A(g) excited state a t about 1.6 times the optical gap. However, in contrast to the PPP res ults, other two-photon states are found in the ab initio calculations to contribute significantly to the cubic polarizability. (C) 1997 Else vier Science B.V.