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Pseudopotential Theory and the Problem of Covalent Bonding. II. Crystals of Si, Ge, and α‐Sn as‐Ordered Systems
Author(s) -
Makhnovetskii A. B.,
Krasko G. L.
Publication year - 1977
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.2220810128
Subject(s) - pseudopotential , brillouin zone , condensed matter physics , covalent bond , lattice (music) , diamond cubic , diamond , crystallography , materials science , molecular physics , chemistry , physics , quantum mechanics , acoustics , composite material
A recently developed theory of the covalent bonding using the Brillouin‐ Wigner perturbation series is applied to the analyses of the static stability of Si, Ge, and α‐Sn crystals with diamond lattice. The model proposed considers the latter as an ordered superstructure arising from the b.c.c. disordered solid solution of the element atoms with vacancies. The calculations of lattice stability are performed firstly for pairwise interaction (second order pseudopotential perturbation theory) and secondly for covalency effects. It is the latter that stabilizes the diamond lattice for the three elements. The spatial covalent charge distribution ϱ cov ( r ) is calculated along the [100], [110] and [111] directions and in (110) plane of the b.c.c. lattice. ϱ cov (r) is shown to have pronounced maxima just in the points where Phillips' “bonding charges” are localized, but being of a more complicated structure with deep holes in the “empty” sites.