Volume 2 Chapter 7 Numeric Sub-menu *RCVOLUME

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*RFACTOR

Function

*RFACTOR is used to test for entries having a specified value or range of values of the R-factor.

CSD Contents

The R-factor is the most widely used measure of the precision of a structure determination. It measures the disagreement between the observed data and the calculated model - the lower the R-factor the more precise the study.

Graphics QUEST3D Procedure

Select *RFACTOR from the NUMERIC sub-menu and respond to the standard numeric prompts.

Basic QUEST Procedure

Ex.

T1 *RFAC 0.001 - 0.05

This test will register hits for all entries having R-factor in the range 0.001-0.05.

Note that we do not use T1 *RFAC .LE. 0.05 since for entries where the R-factor has not been published a value of 0.0 is stored in the CSD.

Related Bit Screens

Database bit screens have been set for convenient ranges of R-factors and these can be used in searches :

Screen 87 : R-factor .LE. 0.120
Screen 88 : R-factor .LE. 0.100
Screen 89 : R-factor .LE. 0.075
Screen 90 : R-factor .LE. 0.050
Screen 91 : R-factor .LE. 0.030
Screen 92 : R-factor not recorded

Ex.

SCRE 89

This query screen will register hits for all entries for which the R-factor is less than or equal to 0.075 ie. 7.5%.

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Volume 2 Chapter 7 Numeric Sub-menu *SIGFLAG.