Several Density Functional Theory Study Of The Raman Probe Molecular Structure And Vibrational Spectra

1. In this paper, the molecular structure and vibrational spectra of 1,4-bis[2-(4-pyridyl)ethenyl]-benzene (BPENB) were studied by five DFT methods. According to our DFT results, it can be infered that it possibly adopts a trans-cis conformation in the cocrystals and metal complex salts. On the basis of the comparison between calculated and experimental results, a superior-relation was obtained. The B3PW91 and B3LYP methods are superior to the others in optimizing structures; In the five DFT methods, BLYP reproduces the observed fundamental frequencies most satisfactorily under the unscaled condition.2. The molecular structure and vibrational frequencies of trans-1,2-bis(4-pyridy1)- ethylene (BPE) were studied by six DFT methods with 6-31++G(d,p) basis set. On the basis of the comparison between calculated and experimental results, a superior- relation was obtained. The B3PW91 method is superior to the others in optimizing structures; Compared the theoretical vibrational frequencies with experimental data, we found that B3PW91/6-31++G(d,p) is good agreement with observed results under the unscaled condition.3. The designed structures of 4-MPY adsorbed on ZnO and ZnS had been studied by means of density functional theory (DFT) methods. Compared the theoretical data and the experimental results, the 4MPY molecule can be deduced to adopt a significantly tilted orientation on the ZnO(ZnS) surface. Combined FT-Raman spectrum, harmonic vibrational frequencies and the normal modes, as well as the vibrational spectra of 4-MPY adsorbed on ZnO(ZnS) are well resolved. And finally, we got charge-transfer mechanism is most likely responsible for the observed enhancement.