Theoretical infrared spectrum and revised assignment for para-nitrophenol. Density functional theory studies Original Research Article

The harmonic vibrational frequencies and infrared intensities of p-nitrophenol as well as geometries of ortho- and para-nitrophenol, are calculated with density functional theory (DFT), using BLYP functional and 6-31G(d,p) basis set. The calculated (unscaled) spectra are in very good agreement with the gas phase and solid IR spectra of p-nitrophenol. A detailed interpretation of the infrared spectra of p-nitrophenol is reported on the basis of the calculated potential energy distribution (PED). Several reassignments have been made.