Low frequency collective vibrational spectra of zwitterionic glycine studied by DFT

Abstract

Fourier transform infrared spectrometer and THz-TDS were used to obtain the experimental spectrum of glycine below 600 cm -1 , and theoretical results of one or more zwitterionic glycine were calculated by DFT at the basis set of b31yp 6-31+g(d,p) level based on Gaussian 03 software package in FIR region. There is more reasonable qualitative agreement between the calculated data of crystalline and observed line positions. Detailed assignments of the observed vibrational frequencies are discussed and the origins of some frequencies are analyzed by contrast. The low frequency collective mode of zwitterionic glycine is affected greatly by the intermolecular interaction and hydrogen-bonding effects and their vibrational modes are collective motion.