Atomic structure and charge transfer in liquid Rb-Te mixtures: Anab initiomolecular-dynamics simulation

Abstract

The structural and electronic properties of liquid ${\mathrm{Rb}}_{x}{\mathrm{Te}}_{1\ensuremath{-}x}$ mixtures $(x=0.0,$ 0.2, and 0.5) are studied by an ab initio molecular-dynamics simulation. It is shown that the transition from metallic to semiconducting states by adding Rb atoms is successfully reproduced as an appearance of a dip at the Fermi level of the calculated electronic density of states, and that this transition is closely related to the structural change in the Te chain. For $x=0.2,$ since the interchain interactions are suppressed by ${\mathrm{Rb}}^{+}$ ions, the Te chains are relatively stabilized in comparison with the pure liquid Te $(x=0.0).$ For $x=0.5,$ more than 50% of Te atoms form ${\mathrm{Te}}_{2}^{2\ensuremath{-}}$ dimers, which are mixed with short Te chains and ${\mathrm{Rb}}^{+}$ ions. It is also shown by calculating the partial density of states that almost complete charge transfer from Rb to Te occurs in the mixtures. The spatial distribution of the transferred charge in the Te chains is obtained and its correlation to the positions of ${\mathrm{Rb}}^{+}$ ions is investigated.