INTERPRETATION OF THE ELECTRONIC ABSORPTION-SPECTRUM OF FREE-BASE PORPHIN BY USING MULTICONFIGURATIONAL 2ND-ORDER PERTURBATION-THEORY

Citation
L. Serranoandres et al., INTERPRETATION OF THE ELECTRONIC ABSORPTION-SPECTRUM OF FREE-BASE PORPHIN BY USING MULTICONFIGURATIONAL 2ND-ORDER PERTURBATION-THEORY, Chemical physics letters, 295(3), 1998, pp. 195-203
Citations number
34
Categorie Soggetti
Physics, Atomic, Molecular & Chemical
Journal title
ISSN journal
00092614
Volume
295
Issue
3
Year of publication
1998
Pages
195 - 203
Database
ISI
SICI code
0009-2614(1998)295:3<195:IOTEAO>2.0.ZU;2-Z
Abstract
Multiconfigurational second-order perturbation (CASPT2) calculations h ave been performed on the low-lying optically allowed valence excited states of the free base porphin molecule in order to assign the four l owest bands of the spectrum. The low-lying triplet states have also be en characterized. A basis set of the atomic natural orbital type of sp lit-valence plus polarization quality for first-row atoms has been emp loyed. Polarization functions are important for an accurate descriptio n of the transitions. These CASPT2 results provide a consistent pictur e of the experimental spectrum. Each band of the spectrum up to 4.5 eV is composed of a pair of states, which become degenerate in the spect ra of metal-porphyrins. Our interpretation deviates from assignments b ased on other types of ab initio calculations. (C) 1998 Elsevier Scien ce B.V. All rights reserved.