1. Introduction
The electronic properties of minerals at high pressure are of substantial physical interest. Periclase (MgO) is one of the major earth-forming minerals. It is easily made by burning magnesium ribbon which oxidizes in a bright white light, resulting in a powder. In nature it is hygroscopic and care must be taken to protect it from moisture. Only one solid phase, with the NaCl-type structure, has been observed for temperature up to the melting and pressures up to 227 GPa [1]. Thus, periclase has traditionally been regarded as a standard solid for calibrating pressure in experiments at extreme conditions [2].
The study of materials at high pressures is experiencing great current activity. High pressure can have a very large effect on the chemical and physical properties of matter and materials often exhibit novel behavior under pressure. As a matter of fact, pressure changes the lattice constant of the material of interest and, hence, produces shifts of the electronic states in the crystal. It can also change the band extrema from one point of the Brillouin zone to another one leading, thus to new electronic properties of the crystal under load [3], [4], [5], [6] and [7]. Pressed MgO is used as an optical material. Experimental investigations of MgO are now possible over considerable ranges of pressure and temperature [2], [8], [9] and [10]. In addition to the experimental advances, reliable computational methods for electronic band structure and total energy calculation have made a substantial impact on high-pressure behavior of MgO [11], [12], [13], [14], [15] and [16].
1. Introduction
The electronic properties of minerals at high pressure are of substantial physical interest. Periclase (MgO) is one of the major earth-forming minerals. It is easily made by burning magnesium ribbon which oxidizes in a bright white light, resulting in a powder. In nature it is hygroscopic and care must be taken to protect it from moisture. Only one solid phase, with the NaCl-type structure, has been observed for temperature up to the melting and pressures up to 227 GPa [1]. Thus, periclase has traditionally been regarded as a standard solid for calibrating pressure in experiments at extreme conditions [2].
The study of materials at high pressures is experiencing great current activity. High pressure can have a very large effect on the chemical and physical properties of matter and materials often exhibit novel behavior under pressure. As a matter of fact, pressure changes the lattice constant of the material of interest and, hence, produces shifts of the electronic states in the crystal. It can also change the band extrema from one point of the Brillouin zone to another one leading, thus to new electronic properties of the crystal under load [3], [4], [5], [6] and [7]. Pressed MgO is used as an optical material. Experimental investigations of MgO are now possible over considerable ranges of pressure and temperature [2], [8], [9] and [10]. In addition to the experimental advances, reliable computational methods for electronic band structure and total energy calculation have made a substantial impact on high-pressure behavior of MgO [11], [12], [13], [14], [15] and [16].
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