Singly and doubly excited states of butadiene, acrolein, and glyoxal: Geometries and electronic spectra

Abstract

Excited-state geometries and electronic spectra of butadiene, acrolein, and glyoxal have been investigated by the symmetry adapted cluster configuration interaction (SAC-CI) method in their s-trans conformation. Valence and Rydberg states below the ionization threshold have been precisely calculated with sufficiently flexible basis sets. Vertical and adiabatic excitation energies were well reproduced and the detailed assignments were given taking account of the second moments. The deviations of the vertical excitation energies from the experiment were less than 0.3 eV for all cases. The SAC-CI geometry optimization has been applied to some valence and Rydberg excited states of these molecules in the planar structure. The optimized ground- and excited-state geometries agree well with the available experimental values; deviations lie within 0.03 A and 0.7 degrees for the bond lengths and angles, respectively. The force acting on the nuclei caused by the excitations has been discussed in detail by calculating the SAC-CI electron density difference between the ground and excited states; the geometry relaxation was well interpreted with the electrostatic force theory. In Rydberg excitations, geometry changes were also noticed. Doubly excited states (so-called 2 (1)A(g) states) were investigated by the SAC-CI general-R method considering up to quadruple excitations. The characteristic geometrical changes and large energetic relaxations were predicted for these states.

Theoretical study of isomerization and decomposition of propenal

“…6 Several theoretical works reported the quantum-chemical calculations for the ground and excited electronic states of propenal [7][8][9][10][11] as well as revealed the locations of S 0 /S 1 and T 1 /T 2 conical intersections and of S/T intersystem crossing points among the lowest four electronic states. 6 Several theoretical works reported the quantum-chemical calculations for the ground and excited electronic states of propenal [7][8][9][10][11] as well as revealed the locations of S 0 /S 1 and T 1 /T 2 conical intersections and of S/T intersystem crossing points among the lowest four electronic states.…”

Obtaining Hartree–Fock and density functional theory doubly excited states with Car–Parrinello density matrix search

“…16 Recent developments in other research groups also show that energies for doubly excited states can be greatly improved with a dressed/ frequency-dependent TDDFT treatment that includes doubly excited determinants. 20,21 Because precise knowledge of excited states is of crucial importance in determining mechanisms of many photochemical processes, a computational inexpensive method for calculation of doubly excited states is needed. Thus, most calculations of doubly excited states 12,13,19 instead use multireference configuration interaction ͑CI͒ methods, such as complete active space self-consistent field ͑CASSCF͒ or symmetry adapted cluster-CI ͑SAC-CI͒.…”

Theory and computations of two-photon absorbing photochromic chromophores

“…At the moment couple cluster methodology provides arguably the best accuracy/cost ratio among wavefunction based methods. The CI method, based on the CC reference (SAC-CI) [102,103] extends this treatment to the excited states. Both single and double (SD-R) [104] and up to sixth-order (General-R) [103] excitation truncation schemes were developed.…”

“…The CI method, based on the CC reference (SAC-CI) [102,103] extends this treatment to the excited states. Both single and double (SD-R) [104] and up to sixth-order (General-R) [103] excitation truncation schemes were developed. Both SD-R and General-R were shown to yield similar results for the 2Ag state of trans-butadiene.…”