Dear Mr. Le Bail,
concerning the discussion caused by Young's e-mail, which was just a call for
proposals, and as a member of the ICDD I want to point out several things:
1. Up to now the PDF database is an identification database for routine powder
diffraction, which is very useful for the scientific community, but much more
important for the majority of the industrial users.
2. For several times the CSD database was mentioned. For further information You
are invited to visit http://www.icdd.com/profile/whatsnew/ccdc.htm, available
since spring 1999. Concerning the aggreement with the FIZ (ICSD) one should note,
that the ICDD is not allowed to add the single crystal data to their entries.
Besides that, it is useless to compare the production rates of single crystal and
powder diffractionists:
- In many cases it is easy to seperate a suitable single crystal out of a
synthesis product, however, it is a different story to establish a reproduceable
synthesis route to obtain several grams of a specified powder material.
- It is known, that many entries in the ICSD database are single crystal data
from non-ambient conditions.
- For many organic and organometallic materials, e.g. large cells, the simulation
of powder patterns is possible, but I do not think that in these problems a
routine powder diffraction is the right choice.
3. As a GIA participant since 1992 I can state that the production of a high
quality pattern submission (*) needs about one week/pattern, whereas the data
collection is the least problem. People always forget, and I have the impression
You are one of them, that the submission of a PDF entry is a part of a quality
control process, i.e. each step of the process should be standardized and as
reproducable as possible. So the more men-hours consuming part of the work is
data calibration, indexing based on Rietveld refinements (if structure is
available), a successful run through the NBSAIDS procedures, and finally the
tedious but very important step of a complete pattern documentation.
4. Therefore it is clear that a useful pattern submission is a time consuming
job, however, this job is a non-scientific work, which cannot included into any
of these impact-factor based evaluations. Consequently many scientists are less
motivated to submit PDF entries. Additionally one should keep in mind that many
ICDD members are working in industrial laboratories.
5. You wrote, You collected about 500 patterns in the last two decades, why didnt
You submit them to the ICDD. It is known to the scientific community, at least
for 10 years, that anyone is cordially invited to submit GIA-proposals of his/her
substances, provided that they are new.
6. The question: Why in Y2K only d(obs) and I(obs) are included in the data base?
Easy answer: This is the minimum information required for a successful
identification. These data are obtained from various literature sources, i.e. the
data are from us, the scientific community. So it is more favourable to encourage
our collegues to publish better data, than hesitating about the quality of some
PDF entries. By the way, for many problems it is better to work with a low
quality entry than with no entry. The addition of several 10000 raw data files
was prevented by the limited mass-storage capacities of PC based systems.
With greetings from Vienna
Christian Lengauer
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# Christian L. Lengauer #
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# Universitaet Wien - Geozentrum #
# Institut fuer Mineralogie und Kristallographie #
# http://www.univie.ac.at/Mineralogie/ #
# Althanstrasse 14, 2B247 #
# A-1090 Wien, Austria #
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# Phone: +431 31336-1843 or -1825 #
# Fax: +431 31336-783 #
# eMail: [EMAIL PROTECTED] #
# [EMAIL PROTECTED] #
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