Title of article :
Vibrational properties of amorphous germanium under pressure and its thermal expansion and Grüneisen parameters
Author/Authors :
Murat Durandurdu، نويسنده , , Murat، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2010
Abstract :
We study the vibrational properties of amorphous germanium at high pressures using a constant pressure ab initio technique. With the application of pressure, the low-frequency modes gradually soften with a decrease in their acoustic-like nature while the high-frequency modes shift to larger frequencies. The acoustic-like vibrations are found to have negative Grüneisen parameters whereas the optic-like ones have positive values of about +1. A negative thermal expansion is produced below 200 K. Furthermore, we find that pressure reduces the number of localized states. Accompanied by the phase transition into a metallic high-density amorphous state, the nature of the low-frequency vibrations is changed from acoustic-like to optic-like and from bond bending to bond stretching.
Keywords :
Modeling and simulation , Amorphous semiconductors , Pressure effects , Thermal Properties
Journal title :
Journal of Non-Crystalline Solids
Journal title :
Journal of Non-Crystalline Solids