Mr-CISD and MR-AQCC calculation of excited states of malonaldehyde: Geometry optimizations using analytical energy gradient methods and a systematic investigation of reference configuration sets

Silmar A. Do Monte, Michal Dallos, Thomas Müller, Hans Lischka

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Extended MR-CISD and MR-AQCC calculations have been performed on the ground state and the first two excited states of malonaldehyde. Full geometry optimizations have been carried for Cs and C2v structures both at MR-CISD and MR-AQCC levels. Vertical and minimum-to-minimum excitation energies and oscillator strengths have been computed. Systematic studies have been undertaken concerning several types of reference spaces. Agreement with the experimental 0-0 transition energy to the S1 state (expt. 3.50 eV, calc. 3.56 eV) and for the vertical excitation to S2 (expt. band maximum 4.71 eV, best estimate 4.86 eV) is very good. In agreement with the CASSCF/CASPT2 results by Sobolewski and Domcke (J. Phys. Chem. A 1999, 103, 4494), we find that the hydrogen bond in malonaldehyde is weakened by excitation to the S1 state. The barrier for proton transfer in the S1 state is increased in comparison with the ground state.

Original languageEnglish
Pages (from-to)447-462
Number of pages16
JournalCollection of Czechoslovak Chemical Communications
Volume68
Issue number3
DOIs
StatePublished - Mar 1 2003

Keywords

  • Ab initio calculations
  • Excited states
  • Hydrogen bond
  • Malonaldehyde
  • Multireference configuration interaction
  • Proton transfer

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