Electric field gradient calculation in V₂O₅

Abstract

AbstractsThe electric field gradient at the "V nucleus in VzO, has been calculated by the .Mulliken-Wolfsberg-Helmholtz method. In contrast to the results obtained from crystal field theory, covalency effects in the MO method are shown to give rise to a valence contribution comparable with the lattice contribution. The total electric field gradient correlates with NMR experiments and confirms the adequacy of the method of calculation used.Le gradient du champ Clectrique au noyau 51V dans V,Os a CtC calculC par la mtthode de Mulliken-Wolfsberg-Helmholtz. Contrairement aux rksultats obtenus de la thCorie du champ cristallin les effets de covalence dans la mCthode MO donnent une contribution de valence comparable 2 celle du rCseau. Le gradient total du champ Clectrique est en bon accord avec les risultats des expkriences RMN ce qui confirme l'aptitude de la mCthode employ Ce. The NMR spectroscopy is known to be the effective method of studying electric and magnetic interactions and the symmetry of the crystal surrounding of a resonating nucleus in a solid. However, the values of chemical shift and nuclear quadrupole interaction tensors obtained from the wide line NMR experiments have no direct relations with peculiarities of the electronic structure of the compound under investigation. Such a dependence can be derived only from the results of theoretical calculations.In the present paper, using vanadium pentoxide as an example, the possibility of applying semiempirical molecular orbital methods to the calculations of the electric field gradient (EFG) at the vanadium nucleus in solid is investigated.The NMR spectra of polycrystalline V205 were obtained using the NMR spectrometer BS-477 (modified for recording wide line spectra) in the frequency 69 1