Structure and bonding in liquid tellurium

The atomic structure and bonding mechanism in liquid tellurium have been investigated by a tight-binding Monte Carlo simulation. On melting, the chain structure of the crystal is preserved in spite of some significant changes in the local atomic environment. A third covalent bond appears with a bond length (widely distributed around 3.15 Aring) intermediate between those characteristic of the crystal. A short-long alternation of the bonds takes place within the chains, in agreement with the most recent extended X-ray-absorption fine structure measurements. In addition, the bond angle within the chains is reduced. Our calculations clearly prove that these effects are due to the electronic interaction between the lone pair orbitals. The subsequent broadening of the lone pair band is responsible for the semiconductor to metal transition that takes place upon melting