The Structural, Electronic and Optical Properties of γ-glycine Under Pressure: A First Principles Study

Non-linear devices and photonics are set to be prevalent in our everyday lives with future applications in quantum optics, plasma physics, and laser manufacturing.The crystallized amino acid γ-glycine is a large band gap insulator that shows promise in the aforementioned fields. In order to better understand its physical properties, the effect of pressure on the structural, electronic and optical properties of γ-glycine were investigated through a first principles calculation approach based on density functional theory. A band gap of 5.026 eV was found, and was shown to decrease with an increase of pressure, due to the widening of the conduction and valence bands which is reaffirmed through the densities of states. Furthermore, the DOS establishes that the conduction bands are mainly dominated by the O 2p and C 2p orbitals and that γ-glycine exhibits electronic stability under 0.0-3.0 GPa. The absorption spectra was calculated using Many-Body Green’s functions GW, which both revealed a slight blueshift in the absorption spectra with an absorption peak in the deep UV region, and verifies the validity of γ-glyince as a prospective candidate for NLOs. The information presented in this paper might be useful in providing insight for the application of γ-glycine in future technology..