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Water monomer interaction with gold nanoclusters from van der Waals density functional theory
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10.1063/1.3675494
/content/aip/journal/jcp/136/2/10.1063/1.3675494
http://aip.metastore.ingenta.com/content/aip/journal/jcp/136/2/10.1063/1.3675494

Figures

Image of FIG. 1.
FIG. 1.

(a) Atomic structure of the gold nanoclusters Aun studied. The first two rows show the planar clusters for n = 6–12. The last row shows the 3D clusters Au17, Au19, and Au20. The left figure in the third row shows the energetically lowest-lying Au18 isomer which has an amorphous structure. The right figure in the third row shows the cage-like Au18 cluster which has a bi-pyramidal structure and is denoted Au18-C. (b) Atomic structure for the benchmark systems of the Au2 cluster (left), the AuH2O (middle), and Au2H2O (right) complexes. The yellow, red, and gray spheres represent Au, O, and H atoms, respectively.

Image of FIG. 2.
FIG. 2.

The upper figure shows the cohesive energy per atom from both PBE and vdW-DF calculations. We also show the results from non-self-consistent vdW calculation at the PBE geometry (“vdW correction”). The middle figure shows the average nearest-neighbor Au-Au bond length. The lower figure shows the HOMO-LUMO gap. The dashed curve with triangular marker (“no vdW”) shows the HOMO-LUMO gap computed by neglecting the non-local vdW correlation from the exchange-correlation energy at the vdW-DF geometry, which cannot be distinguished from the vdW-DF gaps in the scale of the figure. The additional data point at n = 18 refers to the Au18-C cluster, whose cohesive energy is smaller by 0.03 eV/atom, HOMO-LUMO gap is smaller by 0.05 eV and the bond length differs by less than 0.01 Å compared to the amorphous Au18 cluster.

Image of FIG. 3.
FIG. 3.

Projected density of states onto the Au 5d and 6s orbitals for Au12 (a) and Au20 (b) clusters. The upper half of the 5d plot is cut off to show a better view of the 6s plot. The insets show the isosurface plot for the HOMO and LUMO states of the clusters. The vertical lines in the lower figure show the energetic location of the water 1b 1 and 3a 1 orbitals with the insets showing their wavefunction shape.

Image of FIG. 4.
FIG. 4.

Adsorption geometries and energies for corner adsorption. The upper figure on the left shows the adsorption energy. The middle figure on the left show the distance between water O atom and the closest Au corner atom dO-Au. The lower figure on the left shows the adsorption induced change in the average Au–Au nearest-neighbor bond length Δd Au-Au. The additional data point at n = 18 refers to the Au18-C cluster.

Image of FIG. 5.
FIG. 5.

Adsorption geometries and energies for edge adsorption. The adsorption structures shown correspond to the vdW-DF geometry except for the bi-pyramidal Au18-C cluster, where geometry relaxation using PBE (left) and vdW-DF (right) methods leads to different adsorption geometry.

Image of FIG. 6.
FIG. 6.

Adsorption geometries and energies for surface adsorption as in Fig. 5. The middle figure on the left shows the distance between water O atom and the cluster surface onto which water is adsorbed dO-Surface.

Image of FIG. 7.
FIG. 7.

Corner adsorption induced electron redistribution. The left figures show net electron transfer into the water O and H atoms and the nearest-neighbor cluster Au atom to which water is bound from both PBE and vdW-DF calculations. The additional data point at n = 18 refers to the Au18-C cluster. The right figures show isosurface plot of the spatial distribution of electron density difference Δρ for the planar Au12 cluster, the 3D Au18-C and Au20 clusters from vdW-DF calculation. The blue and dark region represents electron accumulation, while the red and light region represents electron depletion.

Image of FIG. 8.
FIG. 8.

Edge adsorption induced electron redistribution as in Fig. 7.

Image of FIG. 9.
FIG. 9.

Surface adsorption induced electron redistribution as in Fig. 7.

Image of FIG. 10.
FIG. 10.

PDOS for corner adsorption onto the planar Au12 and the 3D Au20 clusters. For each cluster, the upper figure shows the density of states projected onto the 5, 6s and sum over the 5d xz and 5d yz (5d xz/yz ) orbitals of the Au atom to which water is bound. The insets show the isosurface plots of the wavefunctions of the HOMO and LUMO states of the interacting system. The lower figure shows the density of states projected onto the three 2p-orbitals of the water O atom and the 1s orbital of the water H atom. The vertical lines in the lower figure show the energetic location of 1b 1 and 3a 1 orbitals for the isolated water molecule. The insets show the wavefunction plot for the states whose energy lies at the corresponding peak position of the PDOS plot as indicated by the arrow.

Image of FIG. 11.
FIG. 11.

PDOS for edge adsorption onto the planar Au12 and the 3D Au20 clusters. For each cluster, the insets in the upper figure show the isosurafce plots of the HOMO and LUMO states of the interacting system. The insets in the lower figure show the wavefunction plots at the corresponding peak positions in the PDOS plot.

Image of FIG. 12.
FIG. 12.

PDOS for surface adsorption onto the planar Au12 and the 3D Au20 clusters. For each cluster, the insets in the upper figure show the isosurafce plots of the HOMO and LUMO states of the interacting system. The insets in the lower figure show the wavefunction plots at the corresponding peak positions in the PDOS plot. The blue (red) region represents positive (negative) value of the wavefunction.

Tables

Generic image for table
Table I.

Comparison between the higher-level quantum chemical calculation and the vdW-DF and PBE calculations on the structure and energetics of the Au2 cluster, the AuH2O and Au2H2O complexes. The corresponding atomic structures are shown in Fig. 1(b). Eb, dAu-Au, dO-Au, and θAu-Water represent the binding energy, the Au–Au bond length, the nearest-neighbor O–Au bond length, the angle between the O–Au bond and the C 2 symmetry axis of the water molecule in the AuH2O and Au2H2O complexes, respectively. For the Au2 cluster, the numbers given in parentheses correspond to those obtained from the relativistic all-electron coupled-cluster method in Ref. 30.

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/content/aip/journal/jcp/136/2/10.1063/1.3675494
2012-01-10
2014-04-19
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Water monomer interaction with gold nanoclusters from van der Waals density functional theory
http://aip.metastore.ingenta.com/content/aip/journal/jcp/136/2/10.1063/1.3675494
10.1063/1.3675494
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