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

Abstract

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[Formula: see text]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[Formula: see text]GPa and 210[Formula: see text]GPa with repeated formations and disconnections. In addition, the [Formula: see text]- and [Formula: see text]-directions of the 2-methyl are stiffer than the [Formula: see text]-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[Formula: see text]GPa. The absorption spectrum of the crystal also indicates that 2-methyl has a relatively high optical activity with the increasing pressure.