An ab initio calculation of the vibronic energies of the CH2+ molecule

1994 ◽  
Vol 72 (11-12) ◽  
pp. 871-878 ◽  
Author(s):  
W. P. Kraemer ◽  
Per Jensen ◽  
P. R. Bunker
Keyword(s):  
Ab Initio ◽  
Electronic State ◽  
Ab Initio Calculation ◽  
Energy Levels ◽  
Morse Oscillator ◽  
Potential Surfaces ◽  
Complete Active Space ◽  
Consistent Field ◽  
Self Consistent Field ◽  
Linear Configuration

In this paper we report the results of an ab initio calculation of vibronic (i.e., N = 0) energy levels of the CH2+ molecular ion giving the lowest 19 levels of the ground [Formula: see text] electronic state and the lowest 15 of the first excited Ã2B1 state. The two electronic states become degenerate (2Π) at the linear configuration and their rovibronic levels interact via the Renner effect. The ab initio calculation of the two potential surfaces was performed at 96 nuclear geometries for the ground electronic state, covering energies up to 11 000 cm−1 above equilibrium, and at 86 geometries for the excited state, covering energies up to 30 000 cm−1 above equilibrium. The multireference configuration interaction (MRCI) level of theory was used with molecular orbital bases that were optimized separately for each state by complete-active-space-self-consistent-field (CASSCF) calculations. The vibronic energy levels were calculated variationally from the potential surfaces using the Morse oscillator rigid bender internal dynamics Hamiltonian modified to include the effects of the Renner interaction. We also present calculated vibronic energies for the CD2+ and CHD+ isotopically substituted molecules.

Spin–orbit ab initio investigation of the UV photoinduced bond cleavage in iodotrimethylstannane

2009 ◽  
Vol 87 (7) ◽  
pp. 1006-1012 ◽  
Author(s):  
N. Ben Amor ◽  
C. Daniel
Keyword(s):  
Ab Initio ◽  
Bond Cleavage ◽  
Ionic Species ◽  
Spin Orbit ◽  
Complete Active Space ◽  
Active Space ◽  
Consistent Field ◽  
Primary Products ◽  
Self Consistent Field ◽  
Electronic Ground

The photoinduced homolytic cleavage of the Sn–I bond in iodotrimethylstannane (CH3)3SnI, observed after UV irradiation, is investigated by means of spin–orbit ab initio calculations based on CASSCF (complete active space self-consistent field) and MS-CASPT2 (multi-state complete active space 2nd order perturbation theory) methods. The absorption electronic spectrum is characterized by ten low-lying 1,3A′ and 1,3A″ spin eigenstates corresponding to py(I),px(I) → σ*SnI; σSnI → σ*SnI and py(Sn), px(Sn) → σ*SnI, where σSnI and σ*SnI are the bonding and anti-bonding orbitals of the Sn–I bond along the pz axis. From the 1A′ electronic ground state and these ten spin eigenstates, 21 spin–orbit states are generated leading to various deactivation channels of (CH3)3SnI, corresponding to the formation of radicals (CH3)3Sn• and •I and to the ionic species (CH3)3Sn+ and I–. Irradiation into the upper band at 175 nm should lead to the heterolytic cleavage of the Sn–I bond to form the ionic primary products exclusively, whereas absorption into the shoulder at 250 nm induces the homolytic breaking with formation of the radical products.

Ab initio calculation of the low-lying electronic states of the ZrN molecule

2012 ◽  
Vol 90 (7) ◽  
pp. 631-639 ◽  
Author(s):  
A. Farhat ◽  
M. Korek ◽  
M.A.L. Marques ◽  
S.N. Abdul-Al
Keyword(s):  
Ab Initio ◽  
Ab Initio Calculation ◽  
Electronic States ◽  
Electronic Energy ◽  
Zirconium Nitride ◽  
Harmonic Frequency ◽  
Complete Active Space ◽  
Self Consistent Field ◽  
First Time ◽  
Good Agreement

An ab initio calculation of the low-lying electronic states of zirconium nitride (ZrN) were performed by using a complete active space self-consistent field with multireference single and double excitation configuration interaction (MRSDCI). The potential energy curves of 21 low-lying electronic states of the ZrN molecule with different spin and spatial symmetries, in the representation 2s+1Λ(+/−) and below 30 000 cm–1, were identified. The harmonic frequency (ωe), the equilibrium internuclear distance (Re), the rotational constants (Be), the electronic energy with respect to the ground state (Te), and the permanent dipole moment (µ) were calculated for the considered electronic states. The comparison of these values with those available in the literature shows a very good agreement with either theoretical or experimental data. Fifteen new electronic states were studied here for the first time.

Metabolite Predictions for Para-Substituted Anisoles Based on ab Initio Complete Active Space Self-Consistent Field Calculations

1995 ◽  
Vol 8 (3) ◽  
pp. 437-443 ◽  
Author(s):  
Marcel J. de Groot ◽  
Gabrieelle M. Donne-Op den Kelder ◽  
Jan N. M. Commandeur ◽  
Joop H. van Lenthe ◽  
Nico P. E. Vermeulen
Keyword(s):  
Ab Initio ◽  
Complete Active Space ◽  
Active Space ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field
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