Vibational Spectroscopic, Molecular Structure and HOMO, LUMO Studies of Sulfanilamide by Density Functional Method

: The molecular geometry and molecular vibrations of Sulfanilamide have been investigated with the aid of quantum chemical calculations, using functional theory (DFT/B3LYP/6-311++G(d,p)/CC-pvdz/Aug-cc-Pvdz) method. The optimized geometrical parameters obtained by all methods show good agreement with experimental X-ray data correction factors, which bring computational frequencies in closer agreement with the experimental data, which have been calculated for predominant vibrational motions of the normal modes at each level of theory. A detailed interpretation of the infrared spectra of Sulfanilamide was also reported. The calculated HOMO and LUMO energies show the occurrence of charge transfer in the molecule. The theoretical spectrogram for FTIR spectra of the title molecule has been constructed.