scholarly journals Hybrid-functional calculations with plane-wave basis sets: Effect of singularity correction on total energies, energy eigenvalues, and defect energy levels

2009 ◽  
Vol 80 (8) ◽  
Author(s):  
Peter Broqvist ◽  
Audrius Alkauskas ◽  
Alfredo Pasquarello
Keyword(s):  
Plane Wave ◽  
Energy Levels ◽  
Basis Sets ◽  
Hybrid Functional ◽  
Defect Energy ◽  
Energy Eigenvalues ◽  
Total Energies

Gaussian basis sets for the atoms from K through Xe

2001 ◽  
Vol 79 (2) ◽  
pp. 121-123 ◽  
Author(s):  
R Centoducatte ◽  
E VR de Castro ◽  
F E Jorge
Keyword(s):  
Key Words ◽  
Ground State ◽  
Basis Sets ◽  
Gaussian Basis Sets ◽  
Hartree Fock ◽  
Generator Coordinate ◽  
Discretization Technique ◽  
Total Energies

An improved generator coordinate Hartree-Fock (IGCHF) method is used to generate Gaussian basis sets for the atoms from K (Z = 19) through Xe (Z = 54). The Griffin-Hill-Wheeler-HF equations are integrated using the integral discretization technique. The ground state HF total energies obtained by us are compared with those calculated with the original GCHF method and with other approaches reported in the literature. The largest difference between our energy values and the corresponding ones computed with a numerical HF method is equal to 6.003 mhartree for Kr (Z = 36).Key words: improved generator coordinate Hartree-Fock method, Gaussian basis sets, total energies.

scholarly journals Models of the interaction of metal tips with insulating surfaces

2012 ◽  
Vol 3 ◽  
pp. 329-335 ◽  
Author(s):  
Thomas Trevethan ◽  
Matthew Watkins ◽  
Alexander L Shluger
Keyword(s):  
Plane Wave ◽  
Density Functional ◽  
Metal Cluster ◽  
Density Functional Theory Calculations ◽  
Basis Sets ◽  
Constant Frequency ◽  
Force Microscopy ◽  
Insulating Surfaces ◽  
Atomic Force ◽  
Tip Model

We present the results of atomistic simulations of metallic atomic-force-microscopy tips interacting with ionic substrates, with atomic resolution. Chromium and tungsten tips are used to image the NaCl(001) and MgO(001) surfaces. The interaction of the tips with the surface is simulated by using density-functional-theory calculations employing a mixed Gaussian and plane-wave basis and cluster-tip models. In each case, the apex of the metal cluster interacts more attractively with anions in the surfaces than with cations, over the range of typical imaging distances, which leads to these sites being imaged as raised features (bright) in constant-frequency-shift images. We compare the results of the interaction of a chromium tip with the NaCl surface, with calculations employing exclusively plane-wave basis sets and a fully periodic tip model, and demonstrate that the electronic structure of the tip model employed can have a significant quantitative effect on calculated forces when the tip and surface are clearly separated.

scholarly journals Analysis of atomic orbital basis sets from the projection of plane-wave results

1996 ◽  
Vol 8 (21) ◽  
pp. 3859-3880 ◽  
Author(s):  
Daniel Sánchez-Portal ◽  
Emilio Artacho ◽  
José M Soler
Keyword(s):  
Plane Wave ◽  
Atomic Orbital ◽  
Basis Sets ◽  
Orbital Basis

Defect Energy Levels in HfO2, ZrO2, La2O3 and SrTiO3

2004 ◽  
Vol 811 ◽  
Author(s):  
K Xiong ◽  
P W Peacock ◽  
J Robertson
Keyword(s):  
Band Gap ◽  
Oxygen Vacancies ◽  
Energy Levels ◽  
Density Approximation ◽  
Weighted Density ◽  
Defect Energy ◽  
High K ◽  
Screened Exchange ◽  
Weighted Density Approximation

AbstractDefect energy levels of oxygen vacancies in various high K oxides HfO2, ZrO2, La2O3 and SrTiO3 have been calculated using methods which give the correct band gap, such as the screened exchange and weighted density approximation.

Negative-U Properties for Point Defects in Silicon

1980 ◽  
Vol 2 ◽  
Author(s):  
G. D. Watkins
Keyword(s):  
Experimental Evidence ◽  
Point Defects ◽  
Electron Irradiation ◽  
Correlation Energy ◽  
Energy Levels ◽  
Unusual Property ◽  
Simple Point ◽  
Normal Order ◽  
Defect Energy ◽  
Lattice Vacancy

ABSTRACTA defect has negative-U properties if it can trap two electrons (or holes) with the second bound more strongly than the first. It is as if there were a net attraction between the two carriers (negative Hubbard correlation energy U) at the defect, and the defect energy levels in the gap are therefore inverted from their normal order. Experimental evidence is presented that interstitial boron and the lattice vacancy, both common simple point defects produced by electron irradiation of silicon, have this unusual property. These defects represent the first and only concrete examples of negative-U centers in any material and serve as models for an understanding of the phenomenon.

scholarly journals Electron-Beam-Induced Current and Cathodoluminescence Study of Dislocations in SrTiO3

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 736
Author(s):  
Wei Yi ◽  
Jun Chen ◽  
Takashi Sekiguchi
Keyword(s):  
Electron Beam ◽  
Resistive Switching ◽  
Oxygen Vacancies ◽  
Energy Levels ◽  
Induced Current ◽  
Temperature Dependent ◽  
Recombination Activity ◽  
Defect Energy ◽  
Electron Beam Induced Current ◽  
Cathodoluminescence Study

Electron-beam-induced current (EBIC) and cathodoluminescence (CL) have been applied to investigate the electrical and optical behaviors of dislocations in SrTiO3. The electrical recombination activity and defect energy levels of dislocations have been deduced from the temperature-dependent EBIC measurement. Dislocations contributed to resistive switching were clarified by bias-dependent EBIC. The distribution of oxygen vacancies around dislocations has been obtained by CL mapping. The correlation between switching, dislocation and oxygen vacancies was discussed.

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