Microscopic Identification of Surface Steps on SiC by Density-Functional Calculations

2020 ◽  
Vol 1004 ◽  
pp. 145-152
Author(s):  
Kaori Seino ◽  
Atsushi Oshiyama
Keyword(s):  
Experimental Observation ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Atomic Steps ◽  
Atomic Structures ◽  
The Past ◽  
Microscopic Identification ◽  
Surface Steps ◽  
Inclined Surfaces ◽  
Lower Terrace

We have performed density-functional calculations in order to clarify atomic structures and energetics of surface steps on SiC. The obtained energetics of distinct step types on vicinal 3C-SiC(111) surfaces which correspond to 4H- and 6H-SiC(0001) surfaces reveals the atom-scale reason for the experimental observation in the past that the step morphology is straight for the SiC(0001) surfaces inclined toward the 〈1-100〉 direction while it is meandering for the 〈11-20〉 inclined surfaces. The calculations clarify the rebonding between upper- and lower-terrace edge atoms, which is decisive for the energetics of the atomic steps.

First Principles Study of Al(100) Twisted Interfaces

2007 ◽  
Vol 129 ◽  
pp. 131-136 ◽  
Author(s):  
Robert Sot ◽  
Jacek Piechota
Keyword(s):  
Molecular Dynamics ◽  
Grain Growth ◽  
First Principles ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Interface Energy ◽  
Orientation Dependence ◽  
Atomic Structures ◽  
First Principles Study

First principles density functional calculations have been performed for a number of Al(100) twisted interfaces with the purpose to investigate the most stable atomic structures. Orientation dependence of interface energy normalized to bulk is established and discussed. The obtained results can be used to model grain growth in molecular dynamics studies.

Forms of Hydrogen and Hydrogen Diffusion in Realistic Models of a-Si:H

2001 ◽  
Vol 664 ◽  
Author(s):  
P. A. Fedders
Keyword(s):  
Ab Initio ◽  
Density Functional Calculations ◽  
Molecular Hydrogen ◽  
Density Functional ◽  
Hydrogen Diffusion ◽  
Dangling Bonds ◽  
The Past ◽  
The Difference

ABSTRACTUsing ab initio density functional calculations we investigate the energetics of hydrogen in a-Si:H starting from a basic supercell that contains 142 atoms and is completely free of defects. The study includes isolated H atoms bonded to dangling bonds, H atoms bonded to dangling bonds in regions of clustered H, bond centered hydrogen, and molecular hydrogen. In particular, the difference between clustered and isolated hydrogen has been largely ignored in the past. Energetics of doped as well as undoped cells are considered. The results are discussed with particular emphasis on H diffusion and the replacement of atoms in molecular hydrogen with those bonded.

Density Functional Calculations of EPR Parameter g Tensors of Some Transition Metal Complexes

2011 ◽  
Vol 2 (2) ◽  
pp. 139-141
Author(s):  
Vinita Prajapati ◽  
◽  
P.L.Verma P.L.Verma ◽  
Dhirendra Prajapati ◽  
B.K.Gupta B.K.Gupta
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Density Functional Calculations ◽  
Density Functional

scholarly journals On the Effects of Doping on the Catalytic Performance of (La,Sr)CoO3. A DFT Study of CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 312 ◽  
Author(s):  
Antonella Glisenti ◽  
Andrea Vittadini
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Catalytic Performance ◽  
Energy Profiles ◽  
High Concentrations ◽  
3D Impurities

The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts.

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