Structural properties and electronic structure ofHgBa2CuO4: Detailed description of the Fermi surface

An ab initio determination of the structural properties and electronic structure of tetragonal ${\mathrm{HgBa}}_2$ ${\mathrm{CuO}}_4$ has been made, within the local-density approximation using the full-potential linear-muffin-tin-orbital method. We find good agreement with the experimental lattice constant and c/a ratio. The band structure exhibits overall features similar to those of other cuprate superconductors with a marked peculiarity, that of an antibonding band coming from the hybridization of Hg p and d and apical oxygen O(2) p states, which lies slightly on top of the Fermi level (${\mathit{E}}_{\mathit{F}}$). This feature has some similarity to what happens in ${\mathrm{Tl}}_2$ ${\mathrm{Ba}}_2$ ${\mathrm{CuO}}_6$. Within this framework a comprehensive description of the character of the states close to and at the Fermi surface is presented.