L-Serine Anhydrous Crystals: Structural, Electronic, and Optical Properties by First-Principles Calculations, and Optical Absorption Measurement

Abstract

The X-ray diffraction data of l-serine anhydrous crystals was taken into account to initialize the total energy minimization process of their unit cell through density functional theory (DFT) computations, which were performed within both the local density and generalized gradient approximations with dispersion, LDA, and GGA+D, respectively. The calculated lattice parameters are in good agreement with the experimental results for the dispersion corrected generalized gradient approximation functional, with a unit cell volume larger by only about 0.32%; the Mulliken and Hirschfield charges show the zwitterionic state of the l-serine molecules in the DFT converged crystals. The electronic (band structure, density of states) and optical absorption properties were calculated to explain the light absorption of the l-serine anhydrous crystalline powder we have measured at room temperature. The optical absorption related to transitions between the top of the valence band and the bottom of the conduction band invo...