Abstract
This work deals with the theoretical study of the molecular structure and vibrational spectra of two well known narcotics-heroin and morphine. The spectra were interpreted with the aid of normal mode analysis following full structure optimization based on the density functional theory and the 6-311G (d, p) basis set combination. A detailed interpretation of the infrared spectra of morphine and heroin is also reported in the present work. The similarities and differences between the vibrational spectra of the two molecules studied have been highlighted. The scaled theoretical wave numbers are in perfect agreement with the experimental values. The thermodynamical calculations related to the two narcotics, namely heroi n and morphine, were also performed at the B3LYP/6-311G (d, p) theoretical level.