An experimental and theoretical vibrational spectra of isoniazide

The molecular structure and vibrational spectra of isoniazide (INH) were calculated by the Density Functional Theory (DFT) method using the B3LYP function with the 6-31++G(d,p) and the Z3PolX basis sets. The representation of the hydrogen bonding effect was achieved with the Polarizable Continuum Model (PCM) including the DFT/B3LYP with the 6-31++G(d,p) basis set. Our calculations were performed with the Gaussian98W package program. The scaled wavenumbers, the modified intensities and the total energy distributions (TED) of the vibrational modes of INH were calculated by using Scale 2.0 program. SQM results showed that the scaling factors were transferable to the similar molecules. The solid phase FT-IR and FT-Raman spectra of INH have been recorded in the range of 4000–450 and 4000–100 cm−1, respectively. The calculated wavenumbers were compared with the corresponding experimental values.