EXPERIMENTAL (FTIR) AND AB INITIO AND DFT STUDY OF VIBRATIONAL FREQUENCIES OF AMINO ACID THREONINE

FTIR spectra of Threonine have been systematically analyzed using ab-initio and density functional theory calculations. The optimized geometries, harmonic vibrational wave numbers and intensity of vibrational bands of Threonine were calculated invoking different basis sets up to HF/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels. Vibrational assignments have been made and calculated DFT frequencies and intensities of the Threonine at B3LYP/6-311++G(d,p) level are found to be in better agreement with corresponding experimental values in comparison to previous results.