Analysis of the hyperfine interactions in the inorganic and coordination compounds by DFT calculations

The main idea of the Townes-Dailey approximation is that the main contribution to the electric field gradient comes from valence electrons of the atom considered. Therefore, we expected that the best nuclear quadrupole coupling constants (QCC) values (i.e. the closest to the experimental results) could be calculated using a nuclear core pseudopotential. A good test of various non-empirical methods also could be the quality of reproduction of NQR parameters such as quadrupole coupling constants and asymmetry parameters. We used B3LYP functional in DFT calculations with 3-21G* and 6-311G** all-electron basis sets. On the other hand we used basis set II, which has a relativistic effective core potential with a (211/211/1) valence basis set for Ti, Nb, Sb, and Sn atoms, 6-311G** all-electron basis set for the H, C, N, S, P, O, Cl atoms. The QCC values have been calculated for diatomic halogens, interhalogens, trihalide ions, organohalogens, molecules and complexes containing B, Al, Ga, In, Sb, Sn, Ti and Nb atoms. The results presented in this work have been calculated use the Gaussian'98 package. The obtained correlation between experimental and calculated QCC values for halogen atoms are valid for all compounds studied, in spite of the different environment of the halogen atoms concerned. Analogous correlations were found for studied compounds containing B, Al, Ga, Sb and Nb atoms with use all-electron basis sets. The QCC values for such heavy atoms as I, Sb, Sn and Nb were close to zero from B3LYP/II calculations. The results confirmed that is impossible to obtain the QCC values for heavy atoms with the DFT performed using the pseudopotential methods.