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00-2-11 Proposed additions to the pdCIF dictionary

  • To: Multiple recipients of list <pddmg@iucr.org>
  • Subject: 00-2-11 Proposed additions to the pdCIF dictionary
  • From: "Brian H. Toby" <brian.toby@nist.gov>
  • Date: Sat, 12 Feb 2000 20:52:37 GMT
Dear members of the pdDMG:

There have been a series of proposed additions to the pdCIF dictionary
that I would like to submit to the pdDMG for discussion. I sincerely
regret that these proposals are "well aged" because I have only a very
limited amount of time for CIF these days. The first four items come
from Robin Shirley, who is doing quite a bit of work in the area of
powder indexing and the remaining two come from Philips Analytical.

Let me first present them, more or less as received, I will add my some
comments in a subsequent e-mail.

00-2-11.1) _pd_proc_quadr_Q

Quadratic form Q=1/d^2^
The derived measure of line position used by most indexing programs.

00-2-11.2) _pd_index_appendix

This section contains descriptive information on the indexing history of
the pattern.

00-2-11.3) _pd_proc_index_merit

Indexing figure of merit for the observed pattern and the chosen set of
cell constants. The type(s) of figure of merit used should be specified.
Previous values (and the associated cell, etc.) can be saved in
_pd_index_appendix.

00-2-11.4) _pd_peak_index_status

A four-character code word showing the status of indexing (or
non-indexing) for the peak.  Some suggested values are `uniq' (uniquely
indexed by a single set of Miller indices), `mult' (multiply indexed by
several possible
sets of Miller indices), `part' (singly indexed because a
multiply-indexed peak has been intensity-partitioned into its
components; do not use `part' for peaks that have been extracted by
deconvolution, which may be flagged as `uniq' or `mult' as the case may
be), `omit' (peak omitted from indexing because from a known secondary
phase or otherwise flagged as unreliable on a priori grounds - not mere
failure to index), `fail' (failed to index).

00-2-11.5) _pd_calib_omega_offset
   _pd_calib_phi_offset
   _pd_calib_chi_offset

Offsets (in degrees) used to calibrate omega, phi and chi (as defined in
_pd_meas_angle_chi _pd_meas_angle_omega and _pd_meas_angle_phi).


00-2-11.6) Storing x-ray tube take-off angle

   How should this be done?


********************************************************************
Brian H. Toby, Ph.D.                    Leader, Crystallography Team
Brian.Toby@NIST.gov      NIST Center for Neutron Research, Stop 8562
voice: 301-975-4297     National Institute of Standards & Technology
FAX: 301-921-9847                        Gaithersburg, MD 20899-8562
********************************************************************

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