The electronic and optical properties of tetrahedral CdSe magic clusters (average diameter ∼1.5 nm) protected by carboxyl and amine ligands, which correspond to previously reported experimental structures, are studied using density functional theory. We find extreme ligand packing densities, capping every single dangling bond of the inorganic core, strong dependence of the Z-type metal carboxylate binding on the amount of excess amine, and potential for improved photoluminescence upon replacing phenyl ligands with alkanes. The computed absorption spectra of the Cd 35 Se 20 cluster agree well with experiments, resolving the 0.2 eV splitting of the first exciton peak due to spin−orbit coupling. We discuss the origin of the significant broadening of the optical spectra as due to phonons and structural variations in the ligand configurations and inorganic core apexes.

The structural, electronic and magnetic properties of small Fe m Rh n clusters having N = m+n ≤ 8 atoms are studied in the framework of a generalized-gradient approximation to density-functional theory. For N = m + n ≤ 6 a thorough sampling of all cluster topologies has been performed, while for N = 7 and 8 only a few representative topologies are considered. In all cases the entire concentration range is systematically investigated. All the clusters show ferromagnetic-like order in the optimized structures. As a result, the average magnetic moment per atom µ N increases monotonously, which is almost linear over a wide range of concentration with Fe content.A remarkable enhancement of the local Fe moments beyond 3 µ B is observed as result of Rh doping. The composition dependence of the binding energy, average magnetic moment and electronic structure are discussed.

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The electronic structure and adsorption properties of 1.5 nm sized Pt, Au, and PtAu nanoclusters are studied by density functional theory. We explain the recent experimental finding that 20% Au content in PtAu nanoparticles is optimal to induce a dramatically different catalytic behavior. Our results show that the d-band center together with the density of states at the Fermi energy can be used as an indicator of the chemical activity of PtAu nanoclusters. The most favorable adsorption sites on the cluster surfaces as a function of the Pt/Au ratio are identified using atomic H as a probe.

Two-dimensional materials with a tunable band gap that covers a wide range of the solar spectrum hold great promise for sunlight harvesting.