745 research outputs found
Electronic shell structure and chemisorption on gold nanoparticles
We use density functional theory (DFT) to investigate the electronic
structure and chemical properties of gold nanoparticles. Different structural
families of clusters are compared. For up to 60 atoms we optimize structures
using DFT-based simulated annealing. Cluster geometries are found to distort
considerably, creating large band gaps at the Fermi level. For up to 200 atoms
we consider structures generated with a simple EMT potential and clusters based
on cuboctahedra and icosahedra. All types of cluster geometry exhibit
jellium-like electronic shell structure. We calculate adsorption energies of
several atoms on the cuboctahedral clusters. Adsorption energies are found to
vary abruptly at magic numbers. Using a Newns-Anderson model we find that the
effect of magic numbers on adsorption energy can be understood from the
location of adsorbate-induced states with respect to the cluster Fermi level.Comment: 14 pages, 18 figure
Modification of the surface electronic and chemical properties of Pt(111) by subsurface 3d transition metals
Ammonia synthesis from N<sub>2</sub> and H<sub>2</sub>O using a lithium cycling electrification strategy at atmospheric pressure
Understanding the apparent fractional charge of protons in the aqueous electrochemical double layer
A detailed atomic-scale description of the electrochemical interface is essential to the understanding of electrochemical energy transformations. In this work, we investigate the charge of solvated protons at the Pt(111) | H_2O and Al(111) | H_2O interfaces. Using semi-local density-functional theory as well as hybrid functionals and embedded correlated wavefunction methods as higher-level benchmarks, we show that the effective charge of a solvated proton in the electrochemical double layer or outer Helmholtz plane at all levels of theory is fractional, when the solvated proton and solvent band edges are aligned correctly with the Fermi level of the metal (E_F). The observed fractional charge in the absence of frontier band misalignment arises from a significant overlap between the proton and the electron density from the metal surface, and results in an energetic difference between protons in bulk solution and those in the outer Helmholtz plane
Quantum-mechanical calculation of H on Ni(001) using a model potential based on first-principles calculations
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