Hartree-Fock Cluster Computations for Ionic Crystals

1985 ◽  
Vol 63 ◽  
Author(s):  
J. M. Vail ◽  
R. Pandey
Keyword(s):  
Shell Model ◽  
Alkaline Earth ◽  
Optical Transition ◽  
Alkali Halides ◽  
Wave Functions ◽  
Ionic Crystals ◽  
Perfect Lattice ◽  
Hartree Fock ◽  
Quantum Cluster ◽  
Model Lattice

ABSTRACTThe ICECAP code is applied to charged and uncharged color centers in alkali halides and alkaline-earth oxides, to test the usefulness of complete-cation pseudopotentials for reproducing the cluster boundary conditions. The physical model includes consistency up to electrostatic octupole order between the Hartree-Fock cluster and the surrounding infinite shell-model lattice. The total energy of the system is determined variationally, including distortion and polarization of the cluster and lattice, and LCAO-MO gaussian-localized cluster wave functions. Electronic states with the lattice unrelaxed are also analysed, yielding color-center optical transition energies. Furthermore, consistency between quantum (cluster) and classical (shell-model) descriptions of the perfect lattice is tested.

Crystal excitation: survey of many-electron Hartree-Fock calculations of self-trapped excitons in insulating crystals

1992 ◽  
Vol 341 (1661) ◽  
pp. 221-231 ◽  
Keyword(s):  
Electronic Structure ◽  
Alkali Halides ◽  
Oxide Materials ◽  
Theoretical Methods ◽  
Hartree Fock ◽  
Cluster Calculations ◽  
Quantum Cluster ◽  
Similarities And Differences

To model successfully the diversity of electronic structure exhibited by excitons in alkali halides and in oxide materials, it is necessary to use a variety or combination of theoretical methods. In this review we restrict our discussion to the results of embedded quantum cluster calculations. By considering the results of such studies, it is possible to recognize the general similarities and differences in detail between the various exciton models in these materials.

scholarly journals An analytical formula for proton momentum distribution in nuclei with A>4

2019 ◽  
Vol 10 ◽  
pp. 248
Author(s):  
G. S. Anagnostatos ◽  
A. N. Antonov ◽  
J. Giapitzakis ◽  
P. Ginis ◽  
S. E. Massen ◽  
...  
Keyword(s):  
Experimental Data ◽  
Shell Model ◽  
Momentum Distribution ◽  
Analytical Formula ◽  
Nucleon Nucleon ◽  
Exotic Nuclei ◽  
Wave Functions ◽  
Proton Momentum ◽  
Correlation Effects ◽  
Hartree Fock

A successful analytical formula for the proton momentum distribution in all nuclei with A>4 accounting for nucleon-nucleon correlation effects, is presented. In this formula the Isomorphic Shell Model wave functions are employed, which are readily available for all nuclei all the way up to 2 0 8Pb. However, other wave functions (e.g., shell model or Hartree-Fock) could be used with almost equivalent results. Available experimental data for 4He, 1 2C and 5 6Fe and predictions of other theories, e.g., for 4 0Ca, are used for comparison of the predictions of the present formula. A reservation is kept concerning the validity of this formula for the momentum distribution of exotic nuclei.

Shell-Model Lattice Dynamics of CsCl, CsBr, and Csl

1972 ◽  
Vol 50 (2) ◽  
pp. 122-128 ◽  
Author(s):  
C. Carabatos ◽  
B. Prevot
Keyword(s):  
Shell Model ◽  
Nearest Neighbor ◽  
Alkali Halides ◽  
Cesium Chloride ◽  
Cesium Iodide ◽  
Frequency Distributions ◽  
Positive Ions ◽  
Cesium Bromide ◽  
Theoretical Predictions ◽  
Model Lattice

Detailed calculations are presented for the frequency distributions and dispersion curves of the three cesium-chloride-structure alkali halides: cesium chloride, cesium bromide, and cesium iodide. In the shell model applied to the study, the polarizabilities of both negative and positive ions have been taken into account as well as the simplified next nearest neighbor interactions. Theoretical predictions and experimental data are in agreement.

The electrostatic calculation of molecular energies - IV. Optimum paired-electron orbitals and the electrostatic method

1956 ◽  
Vol 235 (1201) ◽  
pp. 224-234 ◽  
Keyword(s):  
Simple Procedure ◽  
Wave Functions ◽  
Optimum Form ◽  
Method Of Calculation ◽  
Hartree Fock ◽  
Electron Orbital ◽  
Electrostatic Method ◽  
Valence States ◽  
Paired Electron ◽  
Electrostatic Interpretation

Equations which determine the optimum form of paired-electron orbitals are derived. It is shown that for large nuclear separations these equations become the Hartree-Fock equa­tions for appropriate valence states of the separated atoms. An electrostatic interpretation of chemical bonding is developed using optimum paired-electron orbital functions. For these wave functions this simple procedure yields results identical with those obtained by the conventional method of calculation based on the Hamiltonian integral. Numerical computations by the electrostatic method are also discussed.

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