Structural change of liquid Si15Te85 and Si20Te80 with temperature: Ab initio molecular dynamics simulations

Using ab initio molecular dynamics simulations, the structural and electronic properties of liquid Si15Te85 and Si20Te80 at two temperatures were studied respectively. Compared with available experimental data, the calculated structure factors are acceptable. From symmetry arguments, the calculated partial bond-angle distribution functions suggest that with increasing temperature the extensive tetrahedral network structures persist longer in liquid Si20Te80 than those do in liquid Si15Te85. Our results indicate that the local tetrahedral structure around Si atoms and the Peierls-like distorted local atomic structure around Te atoms both play important roles in the structural change of liquid Si20Te80 and Si15Te85, which also suggest that the mechanisms of the structural change upon cooling in liquid Si20Te80 and Si15Te85 are of no essential difference. The results of DOS and LDOS indicate that the variation of the dip in DOS at EF mainly results from the change of Te p orbitals.