VERTICAL SPECTRUM OF ETHENE, UNCONTRACTED VERSUS CONTRACTED CORRELATION METHODS AND THE ROLE OF THE ADAPTED MOLECULAR-ORBITALS

Authors
PEREZCASANY MP NEBOTGIL I SANCHEZMARIN J MARCOS OC MALRIEU JP
Citation
Mp. Perezcasany et al., VERTICAL SPECTRUM OF ETHENE, UNCONTRACTED VERSUS CONTRACTED CORRELATION METHODS AND THE ROLE OF THE ADAPTED MOLECULAR-ORBITALS, Chemical physics letters, 295(3), 1998, pp. 181-188
Citations number
32
Categorie Soggetti
Physics, Atomic, Molecular & Chemical
Journal title
Chemical physics letters → ACNP
ISSN journal
00092614
Volume
295
Issue
3
Year of publication
1998
Pages
181 - 188
Database
ISI
SICI code
0009-2614(1998)295:3<181:VSOEUV>2.0.ZU;2-I
Abstract
Ethylene vertical excitation energies (VEE) below 9.5 eV have been cal culated with the complete active-space singles and doubles configurati on interaction self-consistent size-consistent dressing (SC)(2)CAS-SDC I. The mean of the absolute deviation from experiment for the calculat ed VEE are 0.14, 0.05 and 0.03 eV for three different molecular orbita l (MO) sets tried. The results show that an uncontracted method and a realistic MO set avoid the difficulties present in the calculation of the strongly mixed Rydberg-valence 1B(1u) states. (C) 1998 Elsevier Sc ience B.V. All rights reserved.