Structural transformation and electronic properties of 2-Methyl-2H-naphtho[1,8-de]triazine under hydrostatic compression

摘要

In this work, the structural, electronic and absorption properties of 2-methyl-2H-naphtho[1,8-de]triazine in the pressure ranges of 0-250 GPa are studied in detail (hereinafter referred to as 2-methyl crystal). Density functional theory (DFT) is used to calculate the lattice constants, bond lengths and bond angles of 2-methyl under different pressures. The results show that the crystals undergo complex transformations under compression, and the major structural transformations occur at pressures of 90 GPa and 210 GPa with repeated formations and disconnections. In addition, the a- and c-directions of the 2-methyl are stiffer than the b-direction, which indicates that the compressibility of the crystal is anisotropic. From the specific analysis of the bandgaps of 2-methyl, we can know that the crystal is converted from semiconductor to metal at 90 GPa. The absorption spectrum of the crystal also indicates that 2-methyl has a relatively high optical activity with the increasing pressure.