In the first paper in this series [Giacovazzo, Burla & Cascarano (1992). Acta Cryst. A48, 901-906], the conditional joint probability distribution function of n phases given p greater-than-or-equal-to n moduli was derived. The properties of the concluding formulae are checked here. It is found that the distribution is not maximized by the correct phases, mostly because of bias in the formulae. If the triplets are estimated via the P10 formula [Cascarano, Giacovazzo, Camalli, Spagna, Burla, Nunzi & Polidori (1984). Acta Cryst. A40, 278-283] instead of being estimated by the Cochran relationship [Cochran (1952). Acta Cryst. 5, 65-67], the situation is remarkably improved but further improvements are needed. A practical procedure is also described that successfully uses phase relationships to solve difficult structures.
The Joint Probability Distribution of Any Set of Phases Given Any Set of Diffraction Magnitudes. II. Practical Applications
BURLA, Maria Cristina;
1992
Abstract
In the first paper in this series [Giacovazzo, Burla & Cascarano (1992). Acta Cryst. A48, 901-906], the conditional joint probability distribution function of n phases given p greater-than-or-equal-to n moduli was derived. The properties of the concluding formulae are checked here. It is found that the distribution is not maximized by the correct phases, mostly because of bias in the formulae. If the triplets are estimated via the P10 formula [Cascarano, Giacovazzo, Camalli, Spagna, Burla, Nunzi & Polidori (1984). Acta Cryst. A40, 278-283] instead of being estimated by the Cochran relationship [Cochran (1952). Acta Cryst. 5, 65-67], the situation is remarkably improved but further improvements are needed. A practical procedure is also described that successfully uses phase relationships to solve difficult structures.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
