Calc. Patterns Quality Marks in Release 2005 Suri Kabekkodu

A calculated patterns quality mark task group was formed during the ICDD spring meeting 2003 in order to develop a method to assign quality marks to calculated patterns. S. Kabekkodu (Chair), C. Hubbard, J. Kaduk, E. Antipov, M. Bennett, P. Wallace, F. Rotella

Scope and Considerations The focus of the quality mark is to determine the confidence level of the structural model used and its impact on the calculated pattern (especially for the purpose of phase identification). The method should involve rigorous crystallographic and additional editorial checks by the ICDD and warning comments from our collaborating structural databases (ICSD/CSD/NIST/LPF).

Program Development Several crystallographic and other data checking programs were developed by the ICDD to achieve this goal. To name a few Temperature factors analysis Non positive definite matrix check Range check Checking the space group choice of origin Composition check (reported Vs refined) Several “keyword” based queries to extract external database comments/warnings

LPF

ICSD

NIST

Population of Editor’s comments after assigning quality mark to all the calculated patterns(394,175) SOURCE DATA NUMBER OF ENTRIES MINOR WARNING SIGNIFICANT WARNING MAJOR WARNING TOTAL LPF ICSD NIST CSD Total