Ab initio calculations of the atomic and electronic structure of MgF2 (011) and (111) surfaces

Open Physics ◽  
2011 ◽  
Vol 9 (2) ◽  
Author(s):  
Anna Vassilyeva ◽  
Robert Eglitis ◽  
Eugene Kotomin ◽  
Alma Dauletbekova
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Optical Band Gap ◽  
Computer Code ◽  
Basis Set ◽  
Considerable Decrease ◽  
Exchange Correlation ◽  
Ionic Nature ◽  
Gaussian Basis Set ◽  
Atomic And Electronic Structure

AbstractThe results of ab initio slab calculations of surface relaxations, rumplings and charge distribution for the different terminations of the MgF2 (011) and (111) polar surfaces are presented and discussed. We have employed the computer code CRYSTAL with the Gaussian basis set and the hybrid B3PW exchange-correlation functional. Despite the ionic nature of the chemical bonding at both surfaces, a considerable decrease of the optical band gap is predicted (1.3 eV or 10%) for the (111) surface as compared to the bulk.

Calculations of Atomic and Electronic Structure for (100) Surfaces of SrTiO3 Perovskite

2002 ◽  
Vol 718 ◽  
Author(s):  
R. I. Eglitis ◽  
E. Heifets ◽  
E. A. Kotomin ◽  
G. Borstel
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Computer Code ◽  
Basis Set ◽  
Surface Relaxation ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Atomic And Electronic Structure

AbstractWe present and discuss main results of the calculations for the surface relaxation and rumpling of SrTiO3 surfaces with TiO2 and SrO terminations using a wide variety of methods of modern computational physics and chemistry, including the shell model (SM) and ab initio methods based on Hartree-Fock (HF) and Density Functional Theory (DFT). The HF and DFT formalisms with different exchange-correlation functionals are implemented into Crystal-98 computer code using a Gaussian-type basis set. We demonstrate that a hybrid B3PW formalism gives the best results for the bulk SrTiO3 properties. Results are compared with previous ab initio plane-wave LDA calculations and LEED experiments. Our calculations demonstrate an increase of the covalency effects between Ti and O atoms near the surface.

AB initio calculation of the atomic and electronic structure for Sb adsorbed on GaAs(110)

1993 ◽  
Vol 43 (9-10) ◽  
pp. 1003-1007 ◽  
Author(s):  
Wolf Gero Schmidt ◽  
Bernd Wenzien ◽  
Friedhelm Bechstedt
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Ab Initio Calculation ◽  
Atomic And Electronic Structure

Ab initio molecular orbital studies of the potential energy curves for the low lying triplet states of Be2 and Be3

1988 ◽  
Vol 66 (8) ◽  
pp. 2034-2040 ◽  
Author(s):  
Ratnakar K. Gosavi ◽  
Otto P. Strausz
Keyword(s):  
Potential Energy ◽  
Triplet State ◽  
Ab Initio ◽  
Potential Energy Curves ◽  
Basis Set ◽  
Triplet States ◽  
Diradical Character ◽  
State Formula ◽  
State Potential ◽  
Gaussian Basis Set

Ab initio calculations with uniform quality gaussian basis set were carried out at the RHF-SCF and CI level on the potential energy curves of the low lying triplet states of Be2 and Be3. The lowest excited state, the [Formula: see text] state of Be2 is 26.0 kcal/mol higher in energy than the ground [Formula: see text] state, and 39.4 kcal/mol lower than the separated Be(1S0) + Be(3P) atoms, with the s, p, d basis set. The next higher triplet state, the 3Πg, is only 8.7 kcal/mol above the lowest [Formula: see text] state. The [Formula: see text] and 3Πu states lie comparatively much higher than the [Formula: see text] state. All the triplet state potential curves have a bonding nature. The lowest triplet state [Formula: see text] in Be3 with D∞h symmetry lies ~15 kcal/mol above the ground [Formula: see text] state, and 48.2 kcal/mol lower than the separated atoms, 2Be(1S0) + Be(3P). The [Formula: see text] state has 1,3-diradical character and in all the higher triplet states α spin electrons are delocalized among the three Be atoms. The next higher triplet state 3Πu is 7.7 kcal/mol above the lowest [Formula: see text] state. The [Formula: see text] and 3Πg states lie much higher than the [Formula: see text] and 3Πu states. Like the triplet states of Be2, all Be3 triplet states have a bonding nature. Reaction path studies on the Be(3P) energy transfer reactions, [Formula: see text] and [Formula: see text] show that these reactions do not feature any activation energy barrier.

Interactions of ions. Ab initio SCF-MO-LCAO calculations of Li+-H2O-OH- with a minimal Gaussian basis set

1975 ◽  
Vol 40 (3) ◽  
pp. 587-596 ◽  
Author(s):  
M. Urban ◽  
S. Pavlík ◽  
V. Kellö ◽  
J. Mardiaková
Keyword(s):  
Ab Initio ◽  
Basis Set ◽  
Gaussian Basis Set

Ab-Initio Molecular Dynamics Approach to the Study of Grain Boundaries in Semiconductors

1988 ◽  
Vol 141 ◽  
Author(s):  
E. Tarnow ◽  
P. D. Bristowe ◽  
J. D. Joannopoulos ◽  
M. C. Payne
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Ab Initio ◽  
Local Density ◽  
Ab Initio Molecular Dynamics ◽  
Local Density Of States ◽  
High Angle ◽  
Surface Information ◽  
Atomic And Electronic Structure ◽  
Translation State

AbstractUsing an ab-initio molecular dynamics approach based on the Car-Parrinello method, the detailed atomic and electronic structure of a high-angle grain boundary in germanium is determined by investigating its energy-translation surface. Information concerning the coordination of the lowest energy configuration, its translation state, volume change, structure factor and local density of states is obtained.

Ab initio fully relativistic molecular calculations: bonding in gold hydride

1986 ◽  
Vol 407 (1833) ◽  
pp. 377-404 ◽  
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Gold Atom ◽  
Basis Set ◽  
Minor Role ◽  
Atomic Unit ◽  
Fundamental Vibration ◽  
Free Gold ◽  
Self Consistent Field ◽  
Extended Basis

The electronic structure of gold hydride is investigated by ab initio fully relativistic extended basis set self-consistent field and configuration interaction calculations based on the Dirac equation. The gold 6p orbitals play only a very minor role in the bonding. The ten electrons occupying the 5d orbitals in the free gold atom are significantly affected by the formation of the molecule whose electronic structure exhibits substantial 5d‒6s hybridization. The extended-basis calculations show that relativity shortens the bond length by 0.45 a. u. (1 a. u. (atomic unit) of length = 1 bohr ≈ 0.529177 × 10 ‒10 m), substantially increases the fundamental vibration frequency and doubles the binding energy predicted by using a single determinant wavefunction. The bonding cannot be fully understood by using non-relativistic theory.

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