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On the computational complexity of determining polyatomic structures by X-rays

✍ Scribed by R.J. Gardner; P. Gritzmann; D. Prangenberg


Publisher
Elsevier Science
Year
2000
Tongue
English
Weight
297 KB
Volume
233
Category
Article
ISSN
0304-3975

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✦ Synopsis


The problem of recovering the structure of crystalline materials from their discrete X-rays is of fundamental interest in many practical applications. An important special case concerns determining the position of atoms of several di erent types in the integer lattice, given the number of each type lying on each line parallel to some lattice directions. We show that the corresponding consistency problem is NP-complete for any two (or more) di erent (ΓΏxed) directions when six (or more) types of atoms are involved.


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Experimental determination of the fine s
✍ D. Coster; G.H. Klamer πŸ“‚ Article πŸ“… 1934 πŸ› Elsevier Science βš– 218 KB

The fine structure of the K-absorption edges of germanium and arsenic, respectively present in the vapours GeCl~ and AsCla, has been determined. In both cases this fine structure is very pronounced and extends to a distance of several hundred volts from the edge. For GeCl, the fine structure is in