Distributed Gaussian Valence Bond Surface Derived from Ab Initio Calculations

2009 ◽  
Vol 5 (4) ◽  
pp. 949-961 ◽  
Author(s):  
Jason L. Sonnenberg ◽  
Kim F. Wong ◽  
Gregory A. Voth ◽  
H. Bernhard Schlegel
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Valence Bond

Generalized valence bond study of rotational singlet structures and pi bond energies for systems containing C==C, Si==Si, and C==Si double bonds

1998 ◽  
Vol 76 (4) ◽  
pp. 477-482 ◽  
Author(s):  
Youliang Wang ◽  
Raymond A Poirier
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Bond Energy ◽  
Valence Bond ◽  
Double Bonds ◽  
Bond Energies ◽  
Fluorine Substitution ◽  
Generalized Valence Bond ◽  
Pi Bonds ◽  
Optimized Geometries

Ab initio GVB(6/12)/6-31G** calculations were performed on A2X==YB2 (A, B = H, F; X, Y = C, Si) to obtain the optimized geometries for planar and twisted singlet structures, and to also calculate pi bond energies (rotational barriers). The nature of C-C, Si-Si, and C-Si pi bonds has been investigated. The results show that the C-C pi bond energy (E pi (ethene) = 65.4 kcal/mol) decreases with increasing fluorine substitution. The pyramidalization at the carbon or silicon center for the twisted structures decreases the pi bond energies in the substituted ethenes and their silicon counterparts. The Si-Si (E pi (disilene) = 23.2 kcal/mol) and C-Si (E pi (silaethene) = 31.6 kcal/mol) pi bonds become much weaker. Fluorine substitution stabilizes both the diradical and the dipolar twisted singlet structures.Key words: pi bond energy, ab initio calculations, generalized valence bond, fluorine substitution, disilene, and silaethene.

ChemInform Abstract: Ab initio Calculations and Qualitative Valence Bond Considerations for H2N-NO2 (Nitramide) and H2N-NO (Nitrosamine).

ChemInform ◽  
2010 ◽  
Vol 32 (44) ◽  
pp. no-no
Author(s):  
Janna Geith ◽  
Thomas M. Klapoetke ◽  
Richard D. Harcourt ◽  
Peter P. Wolynec
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Valence Bond

Ab initio Calculations and Qualitative Valence Bond Considerations for H2N-NO2 (Nitramide) and H2N-NO (Nitrosamine)

2001 ◽  
Vol 56 (7) ◽  
pp. 571-575 ◽  
Author(s):  
Janna Geith ◽  
Thomas M. Klapötke ◽  
Richard D. Harcourt ◽  
Peter P. Wolynec
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Natural Bond Orbital ◽  
Valence Bond ◽  
Nbo Analysis ◽  
Natural Bond Orbital Analysis ◽  
Diffuse Function ◽  
Triple Zeta ◽  
Structure And Bonding ◽  
Orbital Analysis

Abstract The structures, energies and vibrational frequencies of H2N-NO2 and H2N-NO have been calculated at HF, MP2(FC), MP2(FULL) and CISD levels of theory using a polarized triple-zeta 6-311+G(d,p) basis augmented with a diffuse function. In addition, the structures and energies were also computed at the QCISD(T)/6-311+G(d,p) level of theory. The structure and bonding in H2N-NO2 and H2N-NO is discussed on the basis of a Natural Bond Orbital Analysis (NBO analysis) and in addition based on qualitative valence bond (VB) considerations.

Millimetre-wave and infrared spectroscopy of Br13 CN: anharmonic force field of cyanogen bromide from spectroscopic data and ab initio calculations

1997 ◽  
Vol 90 (3) ◽  
pp. 495-497
Author(s):  
CLAUDIO ESPOSTI ◽  
FILIPPO TAMASSIA ◽  
CRISTINA PUZZARINI ◽  
RICCARDO TARRONI ◽  
ZDENEK ZELINGER
Keyword(s):  
Infrared Spectroscopy ◽  
Force Field ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Spectroscopic Data ◽  
Cyanogen Bromide ◽  
Millimetre Wave ◽  
Anharmonic Force
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