Atomistic modeling of amorphous silicon carbide: A first-principles study

Localized basis {\it ab initio} molecular dynamics techniques within density functional theoretic framework have been used to model a realistic atomistic configuration of amorphous silicon carbide ({\it a}-Si$_{0.5}$C$_{0.5}$) containing 1000 atoms. The structural, electronic and vibrational properties have been studied and compared to existing theoretical models and available experimental data. Our study clearly reveals that the short-range chemical order in this material is predominant due to presence of heteronuclear Si-C bonds with coordination defect concentration less than 5\% and the chemical disorder parameter was $\chi$ = 0.083. Our 1000-atom model shows the presence of a clean gap in the spectrum and we also study the nature of the localization of the electronic band tail states as well as the vibrational eigenmodes.