Ab initio molecular dynamics simulations on structure change of liquid Te from normal- to supercooled-state

Using ab initio molecular dynamics simulations and inherent structure formalism, the local atomic structures and electronic properties of liquid Te from the normal- to supercooled-state were studied. The calculated structure factors agree acceptably with available experimental data. There is a noticeable maximum at around 723 K in the curve of first-peak-height of S(Q) versus temperature. With increasing temperature, in the low-temperature region from 573 to 673 K, the average coordination number increases gradually in contrast to the behavior of a classical isotropic fluid; but in the high-temperature region from 843 to 1073 K, it remains nearly constant. Our calculated angular limited bond-bond correlation functions first show that there are two types of Peierls distorted local atomic structures in liquid Te: the lengths of short and long bonds in the first type are similar to those in crystalline Te, while the lengths of short and long bonds in the second one are very different from those in crystalline Te. With decreasing temperature, the lengths of the two short intrachain bonds are unchanged, but those of the two long interchain bonds become longer, indicating that the interchain correlation reduces with decreasing temperature. Our results suggest that the change of the Peierls-type distorted local atomic structures with temperature may be responsible for the striking anomalies of many thermophysical properties of liquid Te. The calculated DOS and LDOS shows that there is an obvious dip in DOS at E-F, but the dip at 1073 K is shallower than that at 573 K. The variation of the dip in DOS mainly results from the change of Te p orbital.