1. Chemistry and Chemical Engineering Department of Mudanjiang Normal University，Mudanjiang 157012, China
2. State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012，China
Abstract：Raman spectroscopy and optimized geometry of the 2-Mercapto-5-nitrobenzimidazole (MNBMZ) molecule had been calculated at density functional B3LYP level using 6-31++g(d,p) basis set in this paper. Raman spectrum was obtained from the calculation results of the frequencies, and compared with the experimental Raman spectrum. The compared results showed that there is a blue shift in the range of 200～800 cm-1，however in the range of 800～8 800 cm-1，there is a red shift. A line of best fit of the experimental Raman frequences versus the calculated ones in the range of 200~1 800 cm-1, the correlation coefficient and the standard deviation were 0.998 and 14.98. The vibrational mode was assigned on the basis of potential energy distribution (PED) through the VEDA4. In addition, the Frontier HOMO-LUMO orbital and the compositions were discussed based on the calculated results，and the HOMO-LUMO gap was estimated to be 3.31 eV，which indicated that the electron will transfer from the HOMO to LUMO. The contribution of S to the HOMO orbital was 52.53%, and the contribution of N and O in nitryl was 23.03, 19.97，19.36 to the HOMO orbital. The excited states were calculated by TDDFT，and the results showed that the adsorption wavelength is 213，281 and 437 nm，but it is 213, 272 and 353 nm especially from the experimental spectrum in the methyl alcohol. This study provided a theoretical support for the analysis of MNBMZ.
Key words：Density functional theory (DFT); Vibrational spectrum; 2-Mercapto-5-nitrobenzimidazole (MNBMZ); Excited states
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