Approximations of the Mulliken charges for the oxygen and silicon atoms of zeolite frameworks calculated with a periodic Hartree–Fock scheme
✍ Scribed by A. V. Larin; D. P. Vercauteren
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 272 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
Distributed multipole analysis DMA on the basis of periodic Ž . Hartree᎐Fock PHF calculations, using the CRYSTAL code, is applied to five different all-siliceous zeolite models: chabazite, gmelinite, merlinoite, montesommaite, and RHO. Mulliken charges of the framework atoms were calculated with a pseudopotential ps-21G* basis set for silicon and a 6-21G* basis for oxygen. The charge values of the silicon atoms were approximated by a simple one-dimensional function with respect to the average Si-O distance within the respective SiO tetrahedra, whereas a two-4 dimensional function with respect to the average Si-O distance and the Si-O-Si angle was used for the oxygen atoms. Both dependences were then utilized to evaluate the Mulliken atomic charges of 10 other frameworks with a larger number of atoms per unit cell. The validity of such application is confirmed by comparison with results obtained through direct PHF calculation for all-siliceous mordenite.