Premium
Perturbation‐Theoretical Model Calculation of the Lattice Mechanics of Ionic Crystals in the Point‐Dipole Approximation
Author(s) -
Basu A. N.,
Sengupta S.
Publication year - 1980
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.2221020108
Subject(s) - ionic crystal , wave function , ionic bonding , dipole , ion , coulomb , lattice (music) , perturbation (astronomy) , crystal (programming language) , physics , statistical physics , quantum mechanics , chemistry , condensed matter physics , molecular physics , computer science , acoustics , programming language , electron
A perturbation‐theoretic model calculation is developed in the point‐dipole approximation for the study of ionic crystals from a knowledge of the Hartree‐Fock wave functions of the free ions that constitute the solid. The salient features of the present calculation are that it a) provides a method for calculating the different lattice static and dynamic properties of a crystal directly from the free ion wave functions without using any crystal property; b) clearly gives an empirical justification for the major assumption of the phenomenological shell model; c) develops a new method for evaluating the Coulomb overlap interaction; d) suggests a modified short‐range polarisation mechanism; and lastly e) shows how far actually the free ion wave functions are realistic as a starting point. The method is applied to calculate a number of lattice mechanical properties of the two ionic crystals namely, NaCl and KCl. Despite the simplicity of the approach the agreement, with observation for both the crystals is quite impressive. The source of the remaining discrepancy is discussed.