First-principles calculations of the structural, dynamical, and electronic properties of liquid MgO

The structural, dynamical, and electronic properties of liquid MgO have been investigated over a wide range of pressure (0 to similar to 240 GPa) and temperature (3000-10 000 K) using first-principles molecular dynamics (FPMD) within the framework of density-functional theory and the pseudopotential approximation. Our results show that the liquid structure is highly sensitive to compression: the Mg-O coordination number increases from 5 at zero pressure to 7 at high pressure. The Gruneisen parameter and heat capacity are found to increase upon twofold compression by 40% and 20%, respectively. The dynamical behavior of the liquid phase is characterized by the diffusion coefficient, which is found to decrease with increasing pressure and to increase with increasing temperature in a way that can be accurately characterized by an Arrhenius relationship with activation energy and volume of 0.85 eV and 1.3 A(3), respectively. The calculated electronic density of states show that the electronic structure of the liquid phase differs substantially from that of the crystalline phase: the liquid has no band gap and a density of states at the Fermi level increases with increasing volume and temperature.