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Anharmonic interactions in diamond‐type crystals
Author(s) -
Jex H.
Publication year - 1971
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.2220450139
Subject(s) - anharmonicity , phonon , thermal expansion , condensed matter physics , diamond , renormalization , vibration , normal mode , power series , order (exchange) , materials science , thermodynamics , physics , quantum mechanics , mathematical analysis , mathematics , finance , economics , composite material
The potential energy of diamond, Si, and Ge crystals has been expanded in a double power series of the infinitesimal strain parameters and phonon coordinates. Third and fourth order expansion coefficients have been fitted to give reasonable agreement with the Grüneisen parameters of the individual modes of vibration, the mean Grüneisen parameters and thermal expansion coefficients, the third order elastic constants and the temperature dependence of the elastic constants. Calculations have been made for the mass operators of normal mode spropagating in the [100] and [111] directions. The relative renormalization of the low energy TA modes in Ge and Si is of the order of 10% while it is one order of magnitude less for phonons of the other branches.