Structural and electronic properties of bulk gibbsite and gibbsite surfaces

Structure and electronic structure of gibbsite and gibbsite surfaces are studied using gradient-corrected density functional theory and a density-functional based tight-binding (DFTB) scheme. The electronic density-of-states (DOS) is insignificantly changed when comparing bulk and single-layer (001) surfaces, but changes for other surfaces, as pentacoordinated Al sites appear. Model structures of other chemically relevant surfaces are proposed, including a stripe and an Al₆(OH )₁₈ cluster model for the (100) face, which turns out to be equivalent to the (011) face if only covalently bound blocks are considered. In all cases quantitative agreement of GGA-DFT and DFTB for structures and occupied electronic states is observed.