Efficient algorithm for the spin-free valence bond theory. I. New strategy and primary expressions

1998 ◽  
Vol 67 (5) ◽  
pp. 287-297 ◽  
Author(s):  
Wei Wu ◽  
Anan Wu ◽  
Yirong Mo ◽  
Menghai Lin ◽  
Qianer Zhang
Keyword(s):  
Efficient Algorithm ◽  
Valence Bond ◽  
Free Valence ◽  
Valence Bond Theory ◽  
New Strategy ◽  
Bond Theory

ELECTRONIC DELOCALIZATION: A QUANTITATIVE STUDY FROM MODERN AB INITIO VALENCE BOND THEORY

2002 ◽  
Vol 01 (01) ◽  
pp. 137-151 ◽  
Author(s):  
YIRONG MO ◽  
LINGCHUN SONG ◽  
WEI WU ◽  
ZEXING CAO ◽  
QIANER ZHANG
Keyword(s):  
Ab Initio ◽  
Valence Bond ◽  
Free Valence ◽  
Matrix Elements ◽  
Resonance Theory ◽  
Valence Bond Theory ◽  
Quantitative Level ◽  
Electronic Delocalization ◽  
Bond Theory ◽  
Overlap Matrix

An ab initio spin-free valence bond code called Xiamen-99 has been developed based on an efficient algorithm called paired-permanent-determinant approach, where Hamiltonian and overlap matrix elements are expressed in terms of paired-permanent-determinants. With this tool, we probed the electronic delocalization phenomenon in a few typical examples including benzene, formamide and ethane. Our computations revealed that ab initio valence bond methods are able to estimate the energetic contribution from the delocalization effect to the stabilization of molecules, thus pave the way to illuminate the resonance theory at the quantitative level. In particular, we analyzed the cyclic electronic delocalization in benzene and showed that different understandings on the resonance may originate from the different usage of one-electron orbitals in the valence bond theory. Our investigation into the hyperconjugative interaction in ethane demonstrated that the hyperconjugation effect is not the dominating factor in the preference of the staggered conformer of ethane.

An efficient algorithm for energy gradients and orbital optimization in valence bond theory

2009 ◽  
Vol 30 (3) ◽  
pp. 399-406 ◽  
Author(s):  
Lingchun Song ◽  
Jinshuai Song ◽  
Yirong Mo ◽  
Wei Wu
Keyword(s):  
Efficient Algorithm ◽  
Valence Bond ◽  
Valence Bond Theory ◽  
Orbital Optimization ◽  
Bond Theory

scholarly journals The electronic structure of carbones revealed: insights from valence bond theory

2021 ◽  
Vol 23 (5) ◽  
pp. 3327-3334
Author(s):  
Remco W. A. Havenith ◽  
Ana V. Cunha ◽  
Johannes E. M. N. Klein ◽  
Francesca Perolari ◽  
Xintao Feng
Keyword(s):  
Electronic Structure ◽  
Valence Bond ◽  
Carbon Suboxide ◽  
Valence Bond Theory ◽  
Bond Theory

Valence bond theory reveals the nature of the OC–C bond in carbon suboxide and related allene compounds.

ChemInform Abstract: Study of the Electronic States of the Benzene Molecule Using Spin- Coupled Valence Bond Theory.

ChemInform ◽  
2010 ◽  
Vol 26 (7) ◽  
pp. no-no
Author(s):  
E. C. DA SILVA ◽  
J. GERRATT ◽  
D. L. COOPER ◽  
M. RAIMONDI
Keyword(s):  
Valence Bond ◽  
Electronic States ◽  
Benzene Molecule ◽  
Valence Bond Theory ◽  
Bond Theory
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