Fourier transform infrared spectra and normal mode analysis of drug molecules: Zidovudine

► The results show that the azide group lies in a nonlinear conformation. ► The azide group also has an anti conformation with respect to both; the hydroxyl group and the thymine ring. ► The calculated frequencies for AZT have been scaled by 0.984, 0.964, 0.959 and 0.952 for BLYP, B3LYP, B3PW91 and MPW1PW91methods respectively. ► The vibrations arises due to atomic displacements of more than one fragments have been also considered and discussed. ► B3LYP method is found to be more near than other methods as compared to experimental one.