Density Functional Theory Investigation on the Molecular Structure and Vibrational Spectra of Triclosan

Density functional theory (DFT) methods possess a strong ability in the molecular modeling of geometrical and spectroscopic parameters because of their high accuracy and consistency with experimental data. In this study, the performances of different DFT methods to predict the molecular structural and vibrational properties of triclosan were investigated and compared. DFT methods comprised of five commonly used functionals, namely B3LYP, LSDA, PBEPBE, CAMB3LYP, and M06-2X, were examined. The proper choice of the basis set had a significant influence on the DFT simulation results. Therefore, the effects of different basis sets, including LANL2DZ, SDD, LANL2MB, 6-311G, and 6-311++G(d,p), on the theoretical calculations of triclosan, were also evaluated. Results revealed that the M062X/6-311++ G(d,p) level of theory was superior to other levels in simulating the structure of triclosan. The LSDA/6311G level of theory showed the best performance in predicting the vibrational spectra of triclosan. These results can provide a fundamental benchmark for the study of environmental pollution mechanisms and ecological effects of triclosan.