Comparative Theoretical Investigation of the Vertical Excitation Energies and the Electronic Structure of [MoVOCl4]-:  Influence of Basis Set and Geometry

2003 ◽  
Vol 42 (13) ◽  
pp. 4046-4056 ◽  
Author(s):  
Victor N. Nemykin ◽  
Partha Basu
Keyword(s):  
Electronic Structure ◽  
Theoretical Investigation ◽  
Basis Set ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Vertical Excitation Energies

The electronic structure of the first row hydrides BH, CH, NH, OH and FH II. Excited states

1959 ◽  
Vol 249 (1258) ◽  
pp. 402-413 ◽  
Keyword(s):  
Electronic Structure ◽  
Excited States ◽  
Electron Correlation ◽  
Ground States ◽  
Oscillator Strengths ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Experimental Values ◽  
Vertical Excitation Energies ◽  
Dipole Length

Previous calculations on the ground states of the hydrides are extended to include the stable excited states. The ab initio orbital calculations predict vertical excitation energies which differ from the experimental values by as much as 2eV. However, when allowance is made for the effects of atomic electron correlation all errors in the calculated excitation energies become less than 0·2eV. The locations of excited states of different multiplicities from those of the ground states are predicted to within this accuracy. The oscillator strengths of allowed transitions from the ground states are calculated using both the dipole-length and dipole-velocity formulae. The dipole-length values are in fair agreement with the only experimental value available (for OH 2 ll → 2 ∑ + ), whereas the dipole-velocity values are much too large. Possible improvements in the accuracy of the calculations are discussed.

The ground state and low-lying excited states of CCCN radical and its ions: a CASSCF/CASPT2 study

2016 ◽  
Vol 94 (9) ◽  
pp. 803-807
Author(s):  
Angyang Yu
Keyword(s):  
Excited States ◽  
Ground State ◽  
Linear Structure ◽  
Electronic Configuration ◽  
Geometric Optimization ◽  
Oscillator Strengths ◽  
Basis Set ◽  
Excitation Energies ◽  
Complete Active Space ◽  
Vertical Excitation

The ground state and low-lying excited states of the CCCN radical and its ions have been investigated systematically using the complete active space self-consistent field (CASSCF) and multi-configuration second-order perturbation theory (CASPT2) methods in conjunction with the ANO-RCC-TZP basis set. The calculated results show that the state 12Σ+ has the lowest CASPT2 energy among the electronic states. By means of the geometric optimization of this radical, it could be found that the molecule exhibits linear structure, with the bond lengths R1 = 1.214 Å, R2 = 1.363 Å, R3 = 1.162 Å, which are very close to the experimental values. The calculated vertical excitation energies and the corresponding oscillator strengths show that there are three relatively strong peaks at energies 0.63, 4.04, and 5.49 eV, which correspond to the transitions 12Σ+ → 12Π, 12Σ+ → 22Π, and 12Σ+ → 22Σ+, respectively. Additionally, the electronic configuration and the harmonic vibration frequencies of each state are also investigated.

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