ISSN:
1600-5724
Quelle:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Thema:
Chemie und Pharmazie
,
Geologie und Paläontologie
,
Physik
Notizen:
Probability calculations confirm a recently proposed formula for the calculation of sin \bar \phihk from Bijvoet inequalities, where \bar \phihk is the average phase of the triple products FhFkF{\bf {\bar h + k}} and F{\bf {\bar h}}, F{\bf {\bar k}}F{\bf {\bar h + k}} [paper I: Kroon, Spek & Krabbendam (1977), Acta Cryst. A33, 382-3851. In paper I it was shown that {\bar \phi}hk could be calculated quite accurately without knowledge of the positions of the anomalous scatterers, provided an appropriate scaling procedure was applied. If the magnitudes of the individual structure factors are considered in addition to the magnitudes of the triple products, an improved formula is obtained which leads to even better results without any scaling procedure. The efficacy of the improved formula is demonstrated by test calculations for the same structure as in paper I (space group P1, two Br ions): (i) the phases of 5139 triple products formed from 322 reflexions (observed) with |E| 〉 1.2 are calculated with a mean error in {\bar \phi}hk of 16° (paper I: 21°), (ii) the phases of 3832 triple products formed from 258 reflexions (calculated) with |E| 〉 1.2 are calculated with a mean error in {\bar \phi}hk of 8° (paper I: 14°). 447
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1107/S0567739478000881
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