Benchmark calculations with correlated molecular wave functions. I. Multireference configuration interaction calculations for the second row diatomic hydrides

1993 ◽  
Vol 99 (3) ◽  
pp. 1914-1929 ◽  
Author(s):  
David E. Woon ◽  
Thom H. Dunning
Keyword(s):  
Configuration Interaction ◽  
Wave Functions ◽  
Configuration Interaction Calculations

The multiphoton spectra of the 1,3-trans-butadiene molecule from AB-initio and configuration interaction calculations

1988 ◽  
Vol 66 (11) ◽  
pp. 2884-2887 ◽  
Author(s):  
Marco Antonio Chaer Nascimento
Keyword(s):  
Ab Initio ◽  
Configuration Interaction ◽  
Wave Functions ◽  
Experimental Results ◽  
Rydberg Series ◽  
Highly Correlated ◽  
Π State ◽  
Configuration Interaction Calculations ◽  
Good Agreement

The multiphoton spectra of the 1,3-trans-butadiene is investigated using highly correlated wave-functions. On the basis of computed transitions energies, intensities and polarization ratios, assignments are made to the first members of five Rydberg series and to a valence (π → π*) state. The results are in good agreement with the experimental results.

Electronic levels in simple conjugated systems III. The significance of configuration interaction

1951 ◽  
Vol 206 (1086) ◽  
pp. 297-308 ◽  
Keyword(s):  
Configuration Interaction ◽  
Transition Probabilities ◽  
Electronic Energy ◽  
Wave Functions ◽  
Electron Systems ◽  
Molecular Systems ◽  
Self Consistent Field ◽  
The One ◽  
Configuration Interaction Calculations ◽  
Better Than

The features of configuration interaction calculations in π -electron systems so far reported are analyzed and compared with some atomic, and diatomic molecular, systems. The interactions between configuration wave functions are not negligible in atoms and are important in molecules bound either by σ - or π -electrons. In the one case where comparison is possible, viz. in H 2 (Coulson 1938), the magnitude of the effect is reduced to one-half when the configurations refer to self-consistent field orbitals rather than to linear combinations of atomic orbitals. The situation in which a consideration of configuration interaction is inescapable is for the configurations of a shell of molecular electrons where, typically, the spread of the energies is small compared with the total electronic energy. In cyclobutadiene, butadiene, benzene and naphthalene, i. e. in all cases so far reported, even the order of some of the states is changed. The wave functions derived in these calculations are markedly better than single-configuration ones, as judged by the much better agreement between calculated and experimental spectral transition probabilities.

The Importance of Photodissociative Trichloromethanol for Atmospheric Chemistry

2003 ◽  
Vol 68 (12) ◽  
pp. 2297-2308 ◽  
Author(s):  
Max Mühlhäuser ◽  
Melanie Schnell ◽  
Sigrid D. Peyerimhoff
Keyword(s):  
Energy Range ◽  
Excited States ◽  
Atmospheric Chemistry ◽  
Configuration Interaction ◽  
Configuration Interaction Calculations

Multireference configuration interaction calculations are carried out for ground and excited states of trichloromethanol to investigate two important photofragmentation processes relevant to atmospheric chemistry. For CCl3OH five low-lying excited states in the energy range between 6.1 and 7.1 eV are found to be highly repulsive for C-Cl elongation leading to Cl2COH (X2A') and Cl (X2P). Photodissociation along C-O cleavage resulting in Cl3C (X2A') and OH (X2Π) has to overcome a barrier of about 0.8 eV (13A'', 11A'') and 1.2 eV (13A') because the low-lying excited states 11A'', 13A' and 13A'' become repulsive only after elongating the C-O bond by about 0.3 Å.

Modification of HAM/3 excitation energies for ΠΠ* transitions of linear molecules

1980 ◽  
Vol 58 (16) ◽  
pp. 1687-1690 ◽  
Author(s):  
Delano P. Chong
Keyword(s):  
Excitation Energy ◽  
Explicit Expression ◽  
Excited States ◽  
Configuration Interaction ◽  
Excitation Energies ◽  
Carbon Suboxide ◽  
Numerical Examples ◽  
Energy Correction ◽  
Linear Molecules ◽  
Configuration Interaction Calculations

The excitation energies calculated by the HAM/3 procedure for ΠΠ* transitions in linear molecules can be internally inconsistent by as much as ± 0.6 eV. In the recent study by Åsbrink etal., the problem was avoided by adopting Recknagel's expressions and requiring the proper average ΠΠ* excitation energy. In this paper, we trace the small inconsistency back to its origin in HAM/3 theory and derive the analytical expression for the energy correction as well as Recknagel's formulas. Numerical examples studied include all seven linear molecules investigated by Åsbrink etal. The explicit expression for the correction enables us to perform meaningful configuration-interaction calculations on the excited states, as illustrated by the carbon suboxide molecule.

scholarly journals Large-scale ab initio configuration interaction calculations for light nuclei

2012 ◽  
Vol 403 ◽  
pp. 012019 ◽  
Author(s):  
Pieter Maris ◽  
H Metin Aktulga ◽  
Mark A Caprio ◽  
Ümit V Çatalyürek ◽  
Esmond G Ng ◽  
...  
Keyword(s):  
Ab Initio ◽  
Configuration Interaction ◽  
Large Scale ◽  
Light Nuclei ◽  
Configuration Interaction Calculations
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