Valence-Electron Density in Silicon and InSb under High Pressure by X-Ray Diffraction

The effects of high pressure on the valence-electron density in silicon and indium antimonide are investigated by x-ray diffraction. It is found that near the transition to the metallic β-tin structure the scattering from the valence electrons sharply decreases, indicating either smearing of the bonding charges or increased anharmonicity in the thermal vibrations.