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.

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.

SPECIFIC HEATS AND DISPERSION CURVES FOR CsCl ON THE BASIS OF THE SHELL MODEL

1967 ◽  
Vol 45 (10) ◽  
pp. 3339-3346 ◽  
Author(s):  
G. P. Srivastava ◽  
B. Dayal
Keyword(s):  
Specific Heat ◽  
Shell Model ◽  
Lattice Dynamics ◽  
Cesium Chloride ◽  
Dispersion Curves ◽  
Experimental Results ◽  
Fair Agreement ◽  
Chloride Crystal ◽  
Specific Heats ◽  
Positive Ions

The shell model of Dick and Overhauser as developed by Cochran and Woods el al. has been applied to study theoretically the lattice dynamics of a cesium chloride crystal. The polarizabilities of both negative and positive ions have been taken into account in this treatment. The charges on the shells of the two ions come out to be of different magnitude. It is seen that the theoretical specific-heat variation with temperature based on this model is in fair agreement with experimental results in the range for which they have been obtained. The theoretical dispersion curves in the three symmetry directions are also given.

Spectroscopic Study of 32S Through the 31P(d,n)32S Reaction

1974 ◽  
Vol 52 (14) ◽  
pp. 1288-1294 ◽  
Author(s):  
A. H. Hussein ◽  
G. C. Neilson ◽  
W. J. McDonald ◽  
W. K. Dawson
Keyword(s):  
Spectroscopic Study ◽  
Shell Model ◽  
Cross Sections ◽  
Differential Cross ◽  
Time Of Flight ◽  
Angular Distributions ◽  
Absolute Differential ◽  
Spectroscopic Factors ◽  
Model Predictions ◽  
Theoretical Predictions

The 31P(d,n)32S reaction has been studied at deuteron energies of 4.0 and 5.45 MeV. Neutron energies were measured by time of flight. Absolute differential cross sections of seven levels in 32S have been measured and compared with the theoretical predictions of both the DWBA and compound statistical theories. Analysis of the angular distributions yielded lP values and absolute spectroscopic factors. These results have been compared with those from other experiments and shell model predictions.

A Deformable Shell Model for the Alkali Halides

1968 ◽  
Vol 29 (1) ◽  
pp. 367-375 ◽  
Author(s):  
A. N. Basu ◽  
S. Sengupta
Keyword(s):  
Shell Model ◽  
Alkali Halides

Excited-Atom Production by Electron Bombardment of Alkali-Halides

1986 ◽  
Vol 75 ◽  
Author(s):  
R. E. Walkup ◽  
Ph. Avouris ◽  
A. P. Ghosh
Keyword(s):  
Gas Phase ◽  
Excited States ◽  
Ground State ◽  
Excited Atom ◽  
Alkali Halides ◽  
Electron Bombardment ◽  
Secondary Electrons ◽  
Excited Atoms ◽  
Positive Ions ◽  
Electronically Excited

AbstractWe present experimental results which suggest a new mechanism for the production of excited atoms and ions by electron bombardment of alkali-halides. Doppler shift measurements show that the electronically excited atoms have a thermal velocity distribution in equilibrium with the surface temperature. Measurements of the absolute yield of excited atoms, the distribution of population among the excited states, and the dependence of yield on incident electron current support a model in which excited atoms are produced by gas-phase collisions between desorbed ground-state atoms and secondary electrons. Similarly, gas-phase ionization of ground-state neutrals by secondary electrons accounts for a substantial portion of the positive ions produced by electron bombardment of alkali-halides.

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