An MO study on 13 C NMR chemical shift and the electronic structure of a three-dimensional polymer crystal by ab initio tight-binding MO theory
| Autor: | Isao Ando, Masahito Uchida, Hiromichi Kurosu, Y. Toida |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Chemistry
Chemical shift Organic Chemistry Ab initio Molecular orbital theory Carbon-13 NMR Analytical Chemistry Inorganic Chemistry Condensed Matter::Materials Science Crystallography Lattice constant Tight binding Condensed Matter::Strongly Correlated Electrons Orthorhombic crystal system Spectroscopy Monoclinic crystal system |
| Zdroj: | Journal of Molecular Structure. 508:181-191 |
| ISSN: | 0022-2860 |
| Popis: | Formulae for calculating the NMR chemical shift of a three-dimensional (3D) polymer crystal were derived by a combination of ab initio tight-binding MO theory and the sum-over-states method of the chemical shift theory. This formalism was applied to the calculation of the 13C NMR chemical shift of 3D polyethylene chains in the orthorhombic and the monoclinic crystallographic forms by using the STO-3G minimal basis set. The effects of inter- and intra-chain interactions on the 13C NMR chemical shift and the band structure were evaluated with a change by means of the a and c axes and the b axis in the lattice constants. The calculated results explain reasonably the experimental data. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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