Ab initio correlation corrections to the Hartree-Fock quasi band-structure of periodic systems employing Wannier-type orbitals

1998 ◽  
Vol 100 (1-4) ◽  
pp. 241-252 ◽  
Author(s):  
Martin Albrecht ◽  
Peter Reinhardt ◽  
Jean-Paul Malrieu
Keyword(s):  
Band Structure ◽  
Ab Initio ◽  
Periodic Systems ◽  
Hartree Fock ◽  
Correlation Corrections

Calculations of Perovskite Surface Relaxation

2000 ◽  
Vol 654 ◽  
Author(s):  
E. Heifets ◽  
E.A. Kotominc ◽  
R.I. Eglitisc ◽  
R.E. Cohen
Keyword(s):  
Thin Films ◽  
Surface Energy ◽  
Ab Initio ◽  
Shell Model ◽  
Electron Correlation ◽  
Surface Relaxation ◽  
Hartree Fock ◽  
Semi Empirical ◽  
Good Agreement ◽  
Correlation Corrections

AbstractThe (100) and (110) surface relaxations are calculated for SrTiO3 and BaTiO3 perovskite thin films by means of a semi-empirical shell model (SM) for different surface terminations. Our SM results for the (100) surface structure are in good agreement with our present ab initio Hartree-Fock calculations with electron correlation corrections, previous ab initio pseudopotential calculationsand LEED experiments. The surface energy for the Ba-, Sr-, TiO- terminated (110) surfaces is found much larger than that for the (100) one. In contrast, the surface energy for the asymmetric O-termination, where outermost O atoms are strongly on-plane displaced, is the lowest for all (110) terminations and thus the most stable.

scholarly journals A Hartree–Fock ab initio band-structure calculation employing Wannier-type orbitals

1998 ◽  
Vol 285 (3-4) ◽  
pp. 174-179 ◽  
Author(s):  
Martin Albrecht ◽  
Alok Shukla ◽  
Michael Dolg ◽  
Peter Fulde ◽  
Hermann Stoll
Keyword(s):  
Band Structure ◽  
Ab Initio ◽  
Structure Calculation ◽  
Band Structure Calculation ◽  
Hartree Fock

Electronic structure of high pressure phase of AlN

1993 ◽  
Vol 8 (8) ◽  
pp. 1922-1927 ◽  
Author(s):  
Ravindra Pandey ◽  
Amin Sutjianto ◽  
Max Seel ◽  
John E. Jaffe
Keyword(s):  
High Pressure ◽  
Electronic Structure ◽  
Band Structure ◽  
Bulk Modulus ◽  
Ab Initio ◽  
Linear Dependence ◽  
Pressure Derivative ◽  
Hartree Fock ◽  
Rocksalt Phase ◽  
Pressure Phase

Results of ab initio Hartree–Fock calculations for the electronic structure of aluminum nitride in the (high-pressure) rocksalt phase are reported. In the rocksalt phase, the calculated lattice constant is 3.982 Å with the bulk modulus of 329 GPa. The band structure is predicted to be indirect at the X point with a gap of 8.9 eV. In this phase, the bonding is shown to be essentially ionic between Al and N. The direct gap shows a stronger linear dependence on pressure with a pressure derivative of 68 meV/GPa compared to that of the indirect gap with a pressure derivative of 31.7 meV/GPa.

Quantum chemical prediction of 2H-pyran vibration spectrum

1990 ◽  
Vol 55 (1) ◽  
pp. 10-20 ◽  
Author(s):  
Stanislav Böhm ◽  
Josef Kuthan
Keyword(s):  
Vibrational Spectrum ◽  
Ab Initio ◽  
Quantum Chemical ◽  
Vibration Spectrum ◽  
Equilibrium Geometry ◽  
Heterocyclic Molecule ◽  
Vibrational Transitions ◽  
Correlation Corrections

Ab initio MO optimalization of the 2H-pyran molecule leads to a defined equilibrium geometry of this so far not identified heterocyclic molecule and to a physical justification of its existence. More advanced nonempirical wavefunctions and temperature corrections indicate that heterocyclic molecule I is energetically less stable than non-cyclic isomers II and III. Wavenumbers of fundamental vibrational transitions of heterocycle I and also known (2E)-2,4-pentadienal (IIIb were calculated using 3-21 G wavefunctions. The vibrational spectrum of compound I is predicted on the basis of correlation corrections.

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