High-pressure stability and insulating performance of MgO: A first-principles insight for geophysical and optoelectronic applications with equation of state

In this study, the dependence on the structural, mechanical, and electronic pressure of magnesium oxide (MgO) was analyzed following the Density Functional Theory (DFT) in the Vienna Ab Initio Simulation Package (VASP). However, in many of those main studies, the focus was on MgO behavior, especially under the application of compression up to 150 GPA. The calculated results closely match the available experimental data for the simulations, and thus, the computational method is considered reasonable for the material's extreme pressure. The structural observation indicates that the lattice constant and size (in unit cell) decrease as a function of pressure: the expected compression of the crystal lattice correlates with this decrease in magnitude of small size. Simultaneously, the bulk modulus grows steeply to indicate that MgO is under still greater load due to compressive pressure, as the atoms are being compressed even more closely together. Extremely high pressure can promote interatomic interaction. In addition to the changes in structure, pressure also affects the electronic properties of MgO. This is because the energy band gap is a function of the higher ambient pressure, shifted from 7.77 eV to ∼10.20 eV at 150 GPA. Moreover, under pressure, MgO becomes more insulating. In addition, phonon dispersion calculations don't have imaginary frequencies throughout the Brillouin zone, which supports the dynamical stability of the rock salt structure at all pressure levels. The very high stability of MgO in extreme conditions is also consistent with this conclusion and suggests its utility in advanced geophysics, optical materials, and high-strength ceramic industries.