The microscopic mechanism of the semiconductor-metal transition in liquid arsenic triselenide

We have clarified the microscopic mechanism of the semiconductor-metal tran sition in liquid As2Se3 with increasing temperature and pressure by means o f ab initio molecular-dynamics simulations. It is shown that, at higher tem peratures, a major part of this liquid mixture consists of twofold chain-li ke structures, while, at lower temperatures, it mainly has a network struct ure, where As and Se atoms have threefold and twofold coordinations, respec tively. Accompanying this structural change, p-like non-bonding states that are almost half-filled are generated around the twofold-coordinated As ato ms, and cause the metallic state of liquid As2Se3.