TY - JOUR
T1 - Mr-CISD and MR-AQCC calculation of excited states of malonaldehyde
T2 - Geometry optimizations using analytical energy gradient methods and a systematic investigation of reference configuration sets
AU - Do Monte, Silmar A.
AU - Dallos, Michal
AU - Müller, Thomas
AU - Lischka, Hans
PY - 2003/3/1
Y1 - 2003/3/1
N2 - 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.
AB - 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.
KW - Ab initio calculations
KW - Excited states
KW - Hydrogen bond
KW - Malonaldehyde
KW - Multireference configuration interaction
KW - Proton transfer
UR - http://www.scopus.com/inward/record.url?scp=0037616594&partnerID=8YFLogxK
U2 - 10.1135/cccc20030447
DO - 10.1135/cccc20030447
M3 - Article
AN - SCOPUS:0037616594
SN - 0010-0765
VL - 68
SP - 447
EP - 462
JO - Collection of Czechoslovak Chemical Communications
JF - Collection of Czechoslovak Chemical Communications
IS - 3
ER -