NMR and NBO calculation of benzimidazoles and pyrimidines: Nano physical parameters investigation

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Six theoretical methods were used for the calculation of physical parameters for derivatives of pyrimidines and benzimidazols. We used Gaussian 98 at NMR and NBO calculations by using HF method with 6-31G, 6-31G* and 6-31+G basis set and B3LYP, BLYP and B3PW91 methods with 6-31G basis set. Chemical shift was drawn curve for all of the atoms in each molecule. The thermo chemical parameters including thermal energy(ΔE), atomic charges, chemical shift anisotropy(δ), asymmetry parameter(η), chemical shift anisotropy(∆σ), dipole orientation, isotropic, anisotropic, NMR determinant and distance matrix compounds. Also the natural bond orbital (NBO) analysis has been performed which seem informative to show some important atomic and structural features. Key words: Benzimidazoles, pyrimidines, NBO analysis, Nano physical parameters.