Structure transformation and electronic properties of m-aminobenzoic acid under different pressures

Abstract

In this paper, the structural, electronic and optical absorption properties of [Formula: see text]-aminobenzoic acid crystals (hereinafter referred to as [Formula: see text]-amino) in the pressure range of 0–300[Formula: see text]GPa are calculated by density functional theory (DFT). The changing trend of the lattice constant of [Formula: see text]-amino under different pressures is analyzed. We find that the crystal undergoes complex transformation. Furthermore, it can be seen that the structure of [Formula: see text]-amino along the [Formula: see text]-axis is stiffer than that along the [Formula: see text]-axis and [Formula: see text]-axis, suggesting that the crystal has anisotropic compressibility. Through the analysis of the band gap and density of states of [Formula: see text]-amino, it is found that the electronic properties of [Formula: see text]-amino are transformed from semiconductor phase to metal phase at 100[Formula: see text]GPa, then jump into the semiconductor phase and maintain the metal phase again in the pressure range of 150–250[Formula: see text]GPa. Repeated phase transitions indicate that the structure of [Formula: see text]-amino becomes more unstable as the pressure increases. Besides, from the absorption spectra, the optical activity of [Formula: see text]-amino is relatively high with the increase of pressure, and two obvious structural transitions are observed at 70 and 270[Formula: see text]GPa, respectively.