Digitale Medien
[S.l.]
:
International Union of Crystallography (IUCr)
Acta crystallographica
40 (1984), S. 668-675
ISSN:
1600-5724
Quelle:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Thema:
Chemie und Pharmazie
,
Geologie und Paläontologie
,
Physik
Notizen:
An extension of existing structure-factor formalisms for anharmonic thermal motion in crystals and the corresponding one-particle potentials is presented and applied to ordered and disordered structures. A generalized probability density function (joint p.d.f.) is introduced and it is first shown that anharmonic temperature factors ('thermal motion') and split positions ('disorder') are mathematically equivalent in describing electron or nuclear densities. When probability densities are interpreted in terms of an effective one-particle potential, however, ordered and disordered structures show different behaviour. For ordered structures the effective one-particle potentials are found to be almost independent of temperature; for disordered structures one obtains a temperature-dependent pseudo potential. The different temperature dependence can be used to distinguish between order and disorder. Pseudo potentials are calculated for several types of disorder and compared with potentials derived from X-ray or neutron diffraction experiments.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1107/S0108767384001379
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