Ab initio study of stabilization of the misfit layer compound ${(\text{PbS})}_{1.14}{\text{TaS}}_{2}$

Ab initio study of stabilization of the misfit layer compound ${(PbS)}_{1.14} {TaS}_{2}$

Evgeniya Kabliman, Peter Blaha, and Karlheinz Schwarz

Phys. Rev. B 82, 125308 – Published 8 September 2010

Abstract

In the present work we perform ab initio electronic-structure calculations of the ${(PbS)}_{1.14} {TaS}_{2}$ misfit layer compound in order to understand the basic mechanism of its stabilization. Density-functional based calculations were carried out in commensurate unit cells containing 74 or 296 atoms using the WIEN2K code. The two experimentally predicted mechanisms of stabilization, namely, metal cross substitution (interchange of Pb and Ta atoms in the PbS and ${TaS}_{2}$ layers) and nonstoichiometry (substitution of Pb by Ta), were investigated. The results show clearly that the nonstoichiometry mechanism plays the significant role. When Pb inside the PbS layer is substituted by Ta with concentrations around 0.13–0.19, a stabilization is found with respect to the parent PbS and ${TaS}_{2}$ compounds. These results are explained by an analysis of partial densities of states. The calculated x-ray photoemission spectroscopy core-level shifts are in reasonable agreement with experiments.