Role of core and valence atomic orbitals in the formation of chemical bonds

1987 ◽  
Vol 22 (5) ◽  
pp. 544-550 ◽  
Author(s):  
G. P. Kostikova ◽  
Yu. P. Kostikov ◽  
D. V. Korol'kov
Keyword(s):  
Chemical Bonds ◽  
Atomic Orbitals

From Atomic Orbitals to Molecular Orbitals and Chemical Bonds

2020 ◽  
pp. 150-187
Author(s):  
Jochen Autschbach
Keyword(s):  
Hydrogen Molecule ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Basis Set ◽  
Orbital Method ◽  
Chemical Bonds ◽  
Atomic Orbitals ◽  
Hartree Fock ◽  
Generalized Matrix

It is shown how an aufbau principle for atoms arises from the Hartree-Fock (HF) treatment with increasing numbers of electrons. The Slater screening rules are introduced. The HF equations for general molecules are not separable in the spatial variables. This requires another approximation, such as the linear combination of atomic orbitals (LCAO) molecular orbital method. The orbitals of molecules are represented in a basis set of known functions, for example atomic orbital (AO)-like functions or plane waves. The HF equation then becomes a generalized matrix pseudo-eigenvalue problem. Solutions are obtained for the hydrogen molecule ion and H2 with a minimal AO basis. The Slater rule for 1s shells is rationalized via the optimal exponent in a minimal 1s basis. The nature of the chemical bond, and specifically the role of the kinetic energy in covalent bonding, are discussed in details with the example of the hydrogen molecule ion.

Charge distributions and chemical effects. XL. Chemical bonds in benzenoid hydrocarbons

1986 ◽  
Vol 64 (2) ◽  
pp. 404-412 ◽  
Author(s):  
S. Fliszár ◽  
G. Cardinal ◽  
N. A. Baykara
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Atomic Charges ◽  
Chemical Bonds ◽  
Benzenoid Hydrocarbons ◽  
Average Deviation ◽  
Chemical Effects ◽  
Local Charge ◽  
Theoretical Results

Benzenoid hydrocarbons were examined using a bond energy scheme featuring the role of atomic charges. The latter were conveniently deduced from appropriate correlations between theoretical results and 13C nuclear magnetic resonance shifts. Atomization energies calculated in this manner agree with their experimental counterparts to within 0.36 kcal mol-1 (average deviation). It appears that benzenoid hydrocarbons can be efficiently described in terms of local charge density properties. In the absence of any distinctive specific feature characterizing benzenoids, this particular description of chemical bonds ultimately results in a unifying genealogy smoothly relating to one another the various possible types of CC and CH bonds which are formed by sp2 and sp3 carbons.

Electron Pairing and Chemical Bonds

1994 ◽  
Vol 59 (3) ◽  
pp. 505-516 ◽  
Author(s):  
Robert Ponec
Keyword(s):  
Molecular Structure ◽  
Quantum Chemical ◽  
Population Analysis ◽  
Structural Formula ◽  
Chemical Bonds ◽  
Electron Pairing ◽  
Theoretical Evidence ◽  
Simple Molecules ◽  
Classical Picture

The recently proposed population analysis of pair densities is applied to the investigation of molecular structure of several simple molecules. The values of pairon populations straightforwardly reproduce the classical structural formula including the multiplicity of the bonds and provide thus the so far missing link between quantum chemical and Lewis's classical picture of bonding. As demonstrated, the formalism of the proposed approach provides strong theoretical evidence for the frequently expected but so far elusive role of electron pairing in chemical bonding.

The role of physical and chemical bonds in the rupture of elastomers

1975 ◽  
Vol 17 (8) ◽  
pp. 1928-1934 ◽  
Author(s):  
M.G. Fal'kovskii ◽  
V.I. Zheleznov ◽  
Yu.A. Antonov ◽  
L.D. Gal'perina ◽  
N.F. Matveyeva
Keyword(s):  
Chemical Bonds ◽  
Physical And Chemical
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