Theoretical study of electron correlation and relativistic effects on spectroscopic constants of hydrogen halides HX (X=F, Cl, Br, I)

2001 ◽  
Vol 599 (1-3) ◽  
pp. 153-162 ◽  
Author(s):  
Alf C. Hennum ◽  
Asger Halkier ◽  
Wim Klopper
Keyword(s):  
Electron Correlation ◽  
Theoretical Study ◽  
Relativistic Effects ◽  
Spectroscopic Constants ◽  
Hydrogen Halides

The Ground State Potential for the Chromium Dimer Revisited

2003 ◽  
Vol 68 (2) ◽  
pp. 265-274 ◽  
Author(s):  
Björn O. Roos
Keyword(s):  
Ground State ◽  
Theoretical Study ◽  
Relativistic Effects ◽  
Basis Set ◽  
Spectroscopic Constants ◽  
Natural Orbital ◽  
State Potential ◽  
Experimental Values ◽  
Atomic Natural Orbital ◽  
Caspt2 Calculations

Results are presented from a new theoretical study of the ground state potential curve of the chromium dimer using multiconfiguration second-order perturbation theory. A new basis set of the atomic natural orbital type is used where the construction includes correlation of the semi-core 3p orbitals and scalar relativistic effects are added using the Douglas-Kroll Hamiltonian. The active space used in the CASSCF/CASPT2 calculations comprised 16 orbitals with 12 active electrons. The resulting ground state potential is in agreement with experiment. Computed spectroscopic constants are (with experimental values within parentheses): Re = 1.66 (1.68) Å, D0 = 1.65 (1.53 ± 0.06) eV, ∆G1/2 = 413 (452) cm-1. Higher vibrational frequencies are also well reproduced.

Theoretical study of the addition of hydrogen halides to olefins: A comparison between (HCl)2and (HF)2additions to ethylene

1987 ◽  
Vol 8 (4) ◽  
pp. 481-488 ◽  
Author(s):  
Carmen Clavero ◽  
Miquel Duran ◽  
Agustí Lledós ◽  
Oscar N. Ventura ◽  
Juan Bertrán
Keyword(s):  
Theoretical Study ◽  
Hydrogen Halides

Theoretical study on the insertion reaction of CH(X2Π) with CH4

1997 ◽  
Vol 75 (7) ◽  
pp. 996-1001 ◽  
Author(s):  
Zhi-Xiang Wang ◽  
Ming-Bao Huang. ◽  
Ruo-Zhuang Liu
Keyword(s):  
Electron Correlation ◽  
Energy Surface ◽  
Theoretical Study ◽  
Reaction Path ◽  
Basis Sets ◽  
Insertion Reaction ◽  
Molecular Orbital Calculations ◽  
Insertion Reactions ◽  
Moller Plesset ◽  
Ch Radical

The CH + CH4 reaction has been studied by means of ab initio molecular orbital calculations incorporating electron correlation with Møller–Plesset perturbation theory up to second and fourth orders with the 6-31G(d,p) and 6-311++G(2d,p) basis sets. An energetically feasible insertion reaction path has been found in the potential energy surface that confirms the experimental proposal for the mechanism of the CH + CH4 reaction. The feature of the mechanism for the CH + CH4 insertion reaction is found to be different from the feature of the mechanisms for the CH + NH3, CH + H2O, and CH + HF insertion reactions, but somewhat similar to that for the CH2 + CH4 insertion reaction. Energetic results for the CH + CH4 reactions are in agreement with experiment. Keywords: CH radical, methane, reaction mechanism.

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