One-phase seminvariants of first rank

Cascarano, G.; Giacovazzo, Carmelo; Calabrese, Gabriele; Burla, Maria Cristina; Nunzi, A.; Polidori, Giampiero; Viterbo, D.

doi:10.1524/zkri.1984.167.1-2.37

Cited by 2 publications

(1 citation statement)

References 5 publications

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“…In the SIR program the estimates of the one-phase structure seminvariants of O 1987 International Union of Crystallography first rank via their second representation are improved via the estimates of a special class of twophase seminvariants (Burla, Nunzi, Giacovazzo & Polidori, 1981). The phase value Ca of any onephase seminvariant is assumed to be distributed according to the von Mises distribution (Cascarano, Giacovazzo, Calabrese, Burla, Nunzi, Polidori & Viterbo, 1984 where 01 is the expected value of ~1. The structure seminvariants with the largest values of G1 are actively used in the phase expansion process, while all the seminvariants cooperate to give the following figure of merit:…”

Section: Introductionmentioning

confidence: 99%

Figures of merit in direct methods: a new point of view

Cascarano¹,

Giacovazzo²,

Viterbo³

1987

Acta Cryst Sect A

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The probabilistic approach has been extensively used for analysing the statistical meanings of some traditional figures of merit. New figures of merit have also been introduced; some exploit one-phase and twophase structure seminvariants of the first rank, the expected negative and/or enantiomorph-sensitive triplet invariants, and the expected negative and/or enantiomorph-sensitive quartets. Other figures of merit exploit the distribution of statistical parameters connected with PSI(0) and active triplets. A new combined figure of merit is shown to be a powerful tool for selecting the correct solutions among the various sets output by multisolution methods.

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Section: Introductionmentioning

confidence: 99%