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An extended deformable shell model for ionic crystals including quadrupolar deformation of the charge cloud
Author(s) -
Ghosh S.,
Basu A. N.,
Sengpta S.
Publication year - 1979
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220940240
Subject(s) - dipole , distortion (music) , deformation (meteorology) , lattice (music) , ion , scalar (mathematics) , ionic bonding , physics , crystal (programming language) , charge (physics) , crystal structure , shell model , condensed matter physics , materials science , crystallography , chemistry , atomic physics , quantum mechanics , geometry , mathematics , computer science , amplifier , optoelectronics , cmos , meteorology , acoustics , programming language
It is well known that the dipolar and scalar deformation of the charge cloud around an ion in ionic crystals are quite significant in describing the different lattice mechanical properties. Even after the inclusion of the above deformations systematic discrepancies between theory and experiment persist. An attempt is made to incorporate the effect of the quadrupolar distortion of the charge cloud in the framework of the deformable shell model. All the relevant equations and lattice sums are evaluated for the CsCl structure and a preliminary application of the complete model which takes into account simultaneously the scalar, the dipolar and the quadrupolar deformation considered for a CsCl structure crystal. So far there is no estimate of the effect of the quadrupolar distortion on the different properties of a crystal belonging to CsCl structure. The calculation indicates that the effect is quite considerable for certain properties and its inclusion improves the overall agreement with experiment.