Ab initio study of vibrational and optical properties of stable ZnmOn(m + n = 2 to 5) nanoclusters

An ab initio study has been performed for the various properties of the most stable configuration out of the various configurations having “m ” number of Zn and “n ” number of O atoms i.e. Zn m O n (m + n = 2 to 5) nanoclusters by employing B3LYP-DFT/6-311G(3df) method. We report here the vibrational frequencies, IR intensities, Rel IR intensities, Raman scattering activities and optical absorption for these nanoclusters. The structure having minimum energy out of all the configurations having similar values of “m ” and “n ” is considered as the most stable. We found that all the different configurations of ZnO4, Zn2O3 and Zn4O complexes are not stable because they possess at least one vibrational frequency which is imaginary. The high vibrational frequencies of each nanocluster arise from the symmetrical and asymmetrical stretching vibrations whereas the lower frequencies belong to the wagging, rocking and the out-of-plane vibrations of Zn and O atoms. Our predicated results for the most intense minimum excitation energies of the ZnO and Zn2O2 nanoclusters exhibit excellent agreement with the available experimental data. All the nanoclusters show strong absorption in the ultraviolet region but some also exhibit weak absorption in the visible region.