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COMCIFS / Powder_Dictionary

CIF definitions for powder diffraction
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cif_pow.dic: definition of the _refln.F_squared_meas data item seems strange #2

Closed vaitkus closed 4 years ago

vaitkus commented 4 years ago

The _refln.F_squared_meas data item is defined both in the cif_pow.dic dictionary and in the cif_core.dic dictionary. However, definition provided in the cif_pow.dic seems strange and causes ambiguities upon merging the dictionaries.

Strange features:

  1. The definition id (_refln.F_squared_meas) and alias ids (_refln.F_meas, _refln.F_meas) seem to refer to different concepts. What is more, the cif_core.dic defines _refln.F_squared_meas and _refln.F_meas data names in two separate save frames. Due to this, merging the cif_core.dic dictionary into the cif_pow.dic results in two save blocks that define the _refln.F_meas data item (the alias id in the save_refln.F_squared_meas frame from the cif_pow.dic and the main id in the save_refln.F_meas frame imported from the cif_core.dic).
  2. The measurement units assigned by the dREL code are not squared (femtometres,volts,electrons) in cif_pow.dic, but squared (femtometre_squared,volt_squared, electron_squared) in cif_core.dic.

I might be missing some convention here, but the merging issue described in 1. seems relevant either way.

jamesrhester commented 4 years ago

This is a straightforward cut and paste error in producing the powder dictionary. Commit 0a48d9e fixes this. _refln.F_squared_meas and _refln.F_meas are different quantities.

vaitkus commented 4 years ago

Great, thank you for the fix.