نتایج جستجو برای: valence bond theory

تعداد نتایج: 859522  

2016
Alagappa Rammohan James A. Kaduk

The crystal structure of sodium potassium hydrogen citrate has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional theory techniques. The Na(+) cation is six-coordinate, with a bond-valence sum of 1.17. The K(+) cation is also six-coordinate, with a bond-valence sum of 1.08. The distorted [NaO6] octahedra share edges, forming chains alo...

Journal: :iranian journal of science and technology (sciences) 2005
m. alavi

in this paper we present our studies using pauling electrostatic bond strength (esb) rules forstructural behaviour, cation vacancies, relation between x, y, and the valence of cations and coordinationin spinel compounds lixmn2o4, 0

2015
Olivier Charles Gagné Frank Christopher Hawthorne

Published two-body bond-valence parameters for cation-oxygen bonds have been evaluated via the root mean-square deviation (RMSD) from the valence-sum rule for 128 cations, using 180,194 filtered bond lengths from 31,489 coordination polyhedra. Values of the RMSD range from 0.033-2.451 v.u. (1.1-40.9% per unit of charge) with a weighted mean of 0.174 v.u. (7.34% per unit of charge). The set of b...

Journal: :Acta crystallographica. Section B, Structural science 2007
Vladimir G Tsirelson Ekaterina V Bartashevich Adam I Stash Vladimir A Potemkin

We present an approach for the determination of covalent bond orders from the experimental electron density and its derivatives at the bond critical points. An application of this method to a series of organic compounds has shown that it provides a bonding quantification that is in reasonable agreement with that obtained by orbital theory. The 'experimental' atomic valence indices are also defi...

Journal: :Annals of Physics 2009

Journal: :Journal of computational chemistry 2007
I. Mayer

The paper accounts for the author's activity in developing bond order and valence indices since the early 80s. These indices represent an important conceptual link between the physical description of molecules as systems of electrons and nuclei and the chemical picture of molecules consisting of atoms kept together by bonds. They are also useful for a systematization and interpretation of the r...

Journal: :EPL (Europhysics Letters) 2008

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