A new computational strategy to calculate the surface energy of a dipolar crystal surface

We used the DACAPO code with the GGA-PW91 approximation to study the adsorption of methyl (CH3) and hydroxyl (OH) for four- and five-layer gold (Au) (001) slabs. We have determined for each species the best binding site, adsorption energy, the change in the work function, surface energy, surface dipole moment, geometrical parameters and projected density of states (PDOS). We performed spin-unpolarized and spin-polarized DFT calculations for free and adsorbed CH3 and OH species. The most important point is that the spin polarization diminishes the adsorption energies but does not change the geometrical parameters. For the CH3 species, only the top site was found to be stable for different coverages. We found that during the optimization phase, the hollow and bridge sites were found to be unstable. In both cases the CH3 species moves toward the top site. We observe that the adsorption energy decreases when increasing the coverage. However, the OH species was stable in all investigated sites (top, bridge and hollow). We notice that the adsorption energy is dependent on the number of slab layers and the bridge is the best site in adsorption energy. The analysis of the calculated O PDOS of OH radical shows a mixing between the O orbitals and the Au bands.

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Ultrathin Platinum Crystal Surface Structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118849 ◽

1985 ◽

Vol 43 ◽

pp. 394-395

Author(s):

R. L. Hines

Keyword(s):

Crystal Surface ◽

Surface Structures ◽

Platinum Surface ◽

Platinum Surfaces ◽

Resolution Level ◽

Experimental Facilities ◽

Carbon Backing ◽

Mesh Grid ◽

Atom Layer

The importance of atom layer terraces or steps on platinum surfaces used for catalysis as discussed by Somorjai justifies an extensive investigation of the structure of platinum surfaces through electron microscopy at the atomic resolution level. Experimental and theoretical difficulties complicate the quantitative determination of platinum surface structures but qualitative observation of surface structures on platinum crystals is now possible with good experimental facilities.Ultrathin platinum crystals with nominal 111 orientation are prepared using the procedure reported by Hines without the application of a carbon backing layer. Platinum films with thicknesses of about ten atom layers are strong enough so that they can be mounted on grids to provide ultrathin platinum crystals for examination of surface structure. Crystals as thin as possible are desired to minimize the theoretical difficulties in analyzing image contrast to determine structure. With the current preparation procedures the crystals frequently cover complete openings on a 400 mesh grid.

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HIGH ACCURACY POTENTIAL ENERGY SURFACE, DIPOLE MOMENT SURFACE, ROVIBRATIONAL ENERGIES AND LINE LIST CALCULATIONS FOR 14NH3

Proceedings of the 72nd International Symposium on Molecular Spectroscopy ◽

10.15278/isms.2017.tj06 ◽

2017 ◽

Author(s):

Phillip Coles ◽

Jonathan Tennyson ◽

Nikolay Zobov ◽

Roman Ovsyannikov ◽

Aleksandra Kyuberis ◽

...

Keyword(s):

Dipole Moment ◽

Potential Energy ◽

Potential Energy Surface ◽

Energy Surface ◽

High Accuracy ◽

Line List ◽

Surface Dipole ◽

Rovibrational Energies

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Anisotropy of Nanoindentation – a tool for the determination of nanocrystal orientation ?

MRS Proceedings ◽

10.1557/proc-779-w5.14 ◽

2003 ◽

Vol 779 ◽

Author(s):

David Christopher ◽

Steven Kenny ◽

Roger Smith ◽

Asta Richter ◽

Bodo Wolf ◽

...

Keyword(s):

Crystal Surface ◽

Scanning Force Microscopy ◽

Depth Range ◽

Dislocation Loops ◽

Force Microscopy ◽

Pile Up ◽

Out Of Plane ◽

Scanning Force ◽

Dynamics Simulations

AbstractThe pile up patterns arising in nanoindentation are shown to be indicative of the sample crystal symmetry. To explain and interpret these patterns, complementary molecular dynamics simulations and experiments have been performed to determine the atomistic mechanisms of the nanoindentation process in single crystal Fe{110}. The simulations show that dislocation loops start from the tip and end on the crystal surface propagating outwards along the four in-plane <111> directions. These loops carry material away from the indenter and form bumps on the surface along these directions separated from the piled-up material around the indenter hole. Atoms also move in the two out-of-plane <111> directions causing propagation of subsurface defects and pile-up around the hole. This finding is confirmed by scanning force microscopy mapping of the imprint, the piling-up pattern proving a suitable indicator of the surface crystallography. Experimental force-depth curves over the depth range of a few nanometers do not appear smooth and show distinct pop-ins. On the sub-nanometer scale these pop-ins are also visible in the simulation curves and occur as a result of the initiation of the dislocation loops from the tip.

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Energies and Electric Dipole Moments of the Bound Vibrational States of HN2+ and DN2+

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20080873 ◽

2008 ◽

Vol 73 (6-7) ◽

pp. 873-897 ◽

Cited By ~ 8

Author(s):

Vladimír Špirko ◽

Ota Bludský ◽

Wolfgang P. Kraemer

Keyword(s):

Dipole Moment ◽

Nearest Neighbor ◽

Energy Surface ◽

Dipole Moments ◽

Three Dimensional ◽

Vibrational States ◽

Spacing Distribution ◽

Triatomic Molecules ◽

Vibrational Levels ◽

Different Levels

The adiabatic three-dimensional potential energy surface and the corresponding dipole moment surface describing the ground electronic state of HN2+ (Χ1Σ+) are calculated at different levels of ab initio theory. The calculations cover the entire bound part of the potential up to its lowest dissociation channel including the isomerization barrier. Energies of all bound vibrational and low-lying ro-vibrational levels are determined in a fully variational procedure using the Suttcliffe-Tennyson Hamiltonian for triatomic molecules. They are in close agreement with the available experimental numbers. From the dipole moment function effective dipoles and transition moments are obtained for all the calculated vibrational and ro-vibrational states. Statistical tools such as the density of states or the nearest-neighbor level spacing distribution (NNSD) are applied to describe and analyse general patterns and characteristics of the energy and dipole results calculated for the massively large number of states of the strongly bound HN2+ ion and its deuterated isotopomer.

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