Structure,energetics,and bonding of amorphous Au-Si alloys

摘要

First principles periodic calculations based on gradient-corrected density functional theory have been performed to examine the structure,energetics,and bonding of amorphous Au-Si alloys with varying Au:Si composition ratios.Our results predict that the Au-Si alloy forms the most stable structure when the Si content is around 40-50 at.%,with an energy gain of about 0.15 eV/atom.In addition,the volume change per atom in the alloy exhibits a distinctive nonlinear trend,with the minimum value around 60 at.% Si.The occurrence of the minimum in the Au-Si mixing energy and volume is attributed to strong hybridization of the Au 5d-Si 3p states.We also present variations in the radial distribution function and atomic coordination number as a function of Au:Si composition ratio,with discussion of the nature of local packing and chemical bonding in the Au-Si alloy system.