Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Valence bond correlation diagram

The formalism of connectivity indices is an embodiment of graph theory. Connectivity indices are intuitively appealing because each index can be calculated exactly from valence bond (Lewis) diagrams familiar to organic chemists, which depict molecular structure in terms of atoms, inner shell and valence shell electrons, valence shell hybridization, o and k electrons, bonds and lone pairs. The indices can then be correlated with physical or chemical properties of interest. Connectivity indices have, in the past, been very useful in treating molecular systems with well-defined chemical formulae and fixed numbers of atoms [24,25]. [Pg.46]

Connectivity indexes in particular may be used easily because each index can be calculated from valence bond diagrams. These indexes can also be correlated... [Pg.215]

THE VALENCE BOND STATE CORRELATION DIAGRAM MODEL 117... [Pg.117]

CONSTRUCTION OF VALENCE BOND STATE CORRELATION DIAGRAMS 119... [Pg.119]

Valence Bond State Correlation Diagrams for Radical Exchange Reactions... [Pg.119]

Some Guidelines for Quantitative Applications of the Valence Bond State Correlation Diagram Model... [Pg.128]

VBSCD Valence bond state correlation diagram. A VB diagram that views the barrier formation as a result of avoided crossing between two state curves that are anchored in the ground and two excited states of reactants and products. The VBSCD is a paradigm for the barrier in chemical reactions (see Chapter 6). [Pg.309]

The BOVB method does not of course aim to compete with the standard ab initio methods. BOVB has its specific domain. It serves as an interface between the quantitative rigor of today s capabilities and the traditional qualitative matrix of concepts of chemistry. As such, it has been mainly devised as a tool for computing diabatic states, with applications to chemical dynamics, chemical reactivity with the VB correlation diagrams, photochemistry, resonance concepts in organic chemistry, reaction mechanisms, and more generally all cases where a valence bond reading of the wave function or the properties of one particular VB structure are desirable in order to understand better the nature of an electronic state. The method has passed its first tests of credibility and is now facing a wide field of future applications. [Pg.222]

Figure 1 Representative valence bond diagrams for benzene, their bit representation using two bits per site, and the integer Ik that encodes these correlated states with six 7r-electrons. The Kekule diagrams 1 > and 2 > are covalent singlets, as is the Dewar diagram 3 >, with one electron at each site. Diagram 4 > is an ionic singlet, while 15 > is a covalent triplet. Figure 1 Representative valence bond diagrams for benzene, their bit representation using two bits per site, and the integer Ik that encodes these correlated states with six 7r-electrons. The Kekule diagrams 1 > and 2 > are covalent singlets, as is the Dewar diagram 3 >, with one electron at each site. Diagram 4 > is an ionic singlet, while 15 > is a covalent triplet.
Predictions can be made about the suitability of different system trajectories on the basis of orbital symmetry conservation rules (207). The most suitable trajectory is an approximation to the reaction path of the reaction under study. The rules can also yield information about the possible structure of the activated complex. The correlation diagram technique has been improved in a series of books by Epiotis et al. (214-216). The method is based on self-consistent field-configuration interaction or valence bond (SCF-CI or VB) (including ionic structures) wave functions. Applications on reactions in the ground states as well as in the excited electronic states are impressive however, the price to be paid for the predictions seems to be rather high. [Pg.273]

Correlation diagram A diagram which shows the relative energies of orbitals, configurations, valence bond structures, or states of reactants and products of a reaction, as a function of the molecular geometry, or another suitable parameter. An example involves the interpolation between the energies obtained for the united atoms and the values for the separated atoms limits. [Pg.306]


See other pages where Valence bond correlation diagram is mentioned: [Pg.404]    [Pg.404]    [Pg.639]    [Pg.73]    [Pg.3]    [Pg.91]    [Pg.103]    [Pg.336]    [Pg.356]    [Pg.202]    [Pg.117]    [Pg.153]    [Pg.155]    [Pg.157]    [Pg.159]    [Pg.161]    [Pg.162]    [Pg.90]    [Pg.487]   
See also in sourсe #XX -- [ Pg.44 , Pg.50 ]




SEARCH



Bond correlation

© 2024 chempedia.info