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Lattice Equilibrium and Phonons in Molybdenum and Tungsten
Author(s) -
Gupta K. C.,
Rathore R. P. S.
Publication year - 1984
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.2221210106
Subject(s) - van der waals force , isotropy , lattice (music) , phonon , tungsten , condensed matter physics , lattice constant , physics , crystal structure , molybdenum , lattice energy , chemistry , thermodynamics , quantum mechanics , molecule , diffraction , crystallography , inorganic chemistry , organic chemistry , acoustics
The deficiencies of the Fielek model, regarding the core‐shell interactions, the volume interactions, and the stability of the lattice, which so far have not been attended adequately, are removed. The improved version treats the lattice under zero stress within the framework of a mathematically more sound equilibrium condition which includes for the first time the van der Waals (vdW) attractive energy in the description of the total energy of the lattice. The vdW three‐body forces are employed in place of Krebs' scheme on account of its deficiency in respect of crystal equilibrium, arbitrary volume dependence of the screening parameter, and the assumption of the perfectly free electron gas. The isotropic force constant of the Fielek model coupling the cores with the d‐shells is replaced by the more realistic two‐body vdW forces. The theoretically sound model thus developed predicts the phonon spectrum in molybdenum and tungsten quite reliably.