Hello, I am experiencing a weird problem with B factor refinement (individual, isotropic) in phenix.refine. The dataset reveals a Wilson B factor of about 23 A². However, if phenix.refine is allowed to run for a number of macrocycles, the mean B value of the model drops continuously to about 9 A². In the end, several atoms are getting values of 0.00! There are no obvious abnormalities in the electron density, and R values are quite good. I was able to dig out an old phenix version (1.7.1) and found that this one behaves perfectly well: mean B around 26 A² (slightly above Wilson B, as is observed frequently) and minimum B around 10 A². So obviously something has happened between versions 1.7.1 and 1.8 ... The latest dev release (1143) shows the same behavior as version 1.8. I should say that this structure is somewhat peculiar (pseudomerohedral twinning plus twofold NCS), but again, the old phenix version handles that without problems. Moreover, the tendency for unreasonably low B factors has been observed recently for a more "conventional" structure in our lab. Any ideas what might be causing this and how to revert to the original behavior? Thanks in advance Oliver ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Forschungszentrum Juelich GmbH 52425 Juelich Sitz der Gesellschaft: Juelich Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDir Dr. Karl Eugen Huthmacher Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender), Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt, Prof. Dr. Sebastian M. Schmidt ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Kennen Sie schon unsere app? http://www.fz-juelich.de/app