Absorption spectra of nucleic acid bases studied by the symmetry-adapted-cluster configuration-interaction (SAC-CI) method

2011 ◽  
Vol 76 (5) ◽  
pp. 537-552 ◽  
Author(s):  
Tomoo Miyahara ◽  
Hiroshi Nakatsuji
Keyword(s):  
Nucleic Acid ◽  
Gas Phase ◽  
Absorption Spectra ◽  
Excited States ◽  
Configuration Interaction ◽  
Nucleic Acid Bases ◽  
Interaction Method ◽  
Configuration Interaction Method ◽  
Cluster Configuration ◽  
Good Agreement

The ground and excited states of five nucleic acid bases (adenine, guanine, cytosine, uracil and thymine) were calculated by employing the SAC/SAC-CI (symmetry adapted cluster/SAC configuration-interaction) method. The absorption spectra with the SAC-CI method were compared with the experimental spectra. The spectra obtained with the SAC-CI method were in good agreement with the experimental spectra in gas phase. Comparisons with the calculations with other methods were made.

Excited electronic states of 1, 3-butadiene

1955 ◽  
Vol 230 (1182) ◽  
pp. 322-330 ◽  
Keyword(s):  
Excited States ◽  
Configuration Interaction ◽  
Energy Levels ◽  
Electronic States ◽  
Interaction Method ◽  
Excited Electronic States ◽  
Configuration Interaction Method ◽  
Self Consistent ◽  
Electronic Wave Function ◽  
Orthogonal Set

Approximate self-consistent orbitals for excited electronic states of cis - and trans -1, 3- butadiene are obtained by a modification of Roothaan’s procedure, in the non-empirical π-electron approximation. The integrals used were evaluated by Parr & Mulliken for calculation of the ground-state electronic wave function. The effects of configuration interaction are calculated by an approximate method and compared with an exact calculation. Molecular orbitals have been obtained both with and without the auxiliary condition that spatial factors of both α and β spin-orbitals should be members of a single orthogonal set. Semiempirical values for the basic integrals, due to Pariser & Parr, have also been used to calculate the energies of excited states by the approximate configuration interaction method. Energy levels derived from the Pariser-Parr integrals are in close agreement with observed levels, which differ considerably from those calculated from the Parr-Mulliken non-empirical integrals.

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