Semiconductor–metal transition in liquid arsenic chalcogenides by ab initio molecular-dynamics simulations

Abstract The microscopic mechanism of the semiconductor–metal transition in the liquid arsenic chalcogenides, As 2 S 3 , As 2 Se 3 , and As 2 Te 3 , with increasing temperature and pressure is studied by means of ab initio molecular-dynamics simulations. It is shown that in the liquids As 2 S 3 and As 2 Se 3 the network structure is transformed into a two-fold chain-like structure at higher temperatures, while in the liquid As 2 Te 3 the four-fold coordinated As and the three-fold coordinated Te increase in the network structure with increasing temperature. For the metallization of the liquids As 2 S 3 and As 2 Se 3 , the electronic states around the lower-coordinated atoms are essential. On the other hand, the electronic states around the Te atoms contribute importantly to metallization in the liquid As 2 Te 3 .