Vibrational spectroscopy investigation using ab initio and density functional theory analysis on the structure of 2,4,6-trinitrophenol

Quantum chemical calculations of the equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities of 2,4,6-trinitrophenol (TNP, C6H3N3O7) in the ground state were carried out by using ab initio HF and density functional theory (DFT/B3LYP) methods with 6-311++G** basis set. The research shows that the presence of strong hydrogen bonding in the title compound. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared spectrum of TNP is also reported. The theoretical spectrograms for FT-IR of the title compound have been constructed. In addition, the HOMO and LUMO energies are also calculated.