dbo:abstract
|
- In crystallography, the Sayre equation, named after David Sayre who introduced it in 1952, is a mathematical relationship that allows one to calculate probable values for the phases of some diffracted beams. It is used when employing direct methods to solve a structure. Its formulation is the following: which states how the structure factor for a beam can be calculated as the sum of the products of pairs of structure factors whose indices sum to the desired values of . Since weak diffracted beams will contribute a little to the sum, this method can be a powerful way of finding the phase of related beams, if some of the initial phases are already known by other methods. In particular, for three such related beams in a centrosymmetric structure, the phases can only be 0 or and the Sayre equation reduces to the triplet relationship: where the indicates the sign of the structure factor (positive if the phase is 0 and negative if it is ) and the sign indicates that there is a certain degree of probability that the relationship is true, which becomes higher the stronger the beams are. (en)
|
dbo:wikiPageID
| |
dbo:wikiPageLength
|
- 1852 (xsd:nonNegativeInteger)
|
dbo:wikiPageRevisionID
| |
dbo:wikiPageWikiLink
| |
dbp:wikiPageUsesTemplate
| |
dcterms:subject
| |
rdfs:comment
|
- In crystallography, the Sayre equation, named after David Sayre who introduced it in 1952, is a mathematical relationship that allows one to calculate probable values for the phases of some diffracted beams. It is used when employing direct methods to solve a structure. Its formulation is the following: In particular, for three such related beams in a centrosymmetric structure, the phases can only be 0 or and the Sayre equation reduces to the triplet relationship: (en)
|
rdfs:label
| |
owl:sameAs
| |
prov:wasDerivedFrom
| |
foaf:isPrimaryTopicOf
| |
is dbo:knownFor
of | |
is dbo:wikiPageWikiLink
of | |
is dbp:knownFor
of | |
is foaf:primaryTopic
of | |