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Unsymmetrized Self‐Consistent Field Approximation for Strongly Anharmonic Crystals with Taking into Account the Polarizability of the Ions
Author(s) -
Zubov V. I.,
Sh. Soulayman S.
Publication year - 1981
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.2221040142
Subject(s) - anharmonicity , polarizability , ion , ionic bonding , adiabatic process , physics , adiabatic theorem , helmholtz free energy , metastability , crystal (programming language) , atomic physics , condensed matter physics , chemistry , quantum mechanics , molecule , computer science , programming language
The unsymmetrized self‐consistent field method for strongly anharmonic (nonmetallic) crystals is improved by taking into account the ionic polarization caused by the displacement of the outer electron shell relative to the ionic core during the oscillations of the ions. The self‐consistent potential and the Helmholtz free energy of a strongly anharmonic crystal are found using the adiabatic approximation. In the case of the strong anharmonicity of fourth order, the equations of state of a diatomic crystal are obtained. In the zeroth approximation, the inclusion of the ionic polarizability leads to an added renormalization of the force coefficients of second order. The corrections to the Helmholtz free energy and to the equations of state are considered.