At 03:04 02/08/2013 -0700, Leonid Solovyov wrote:
>remember the previous discussion at the
>Rietveld list where he claimed that all H
>can be seen and refined independently, always.
Absurd - never said so.
From absurdity and crimes we arrived at falsifications?
Below are the unfalsified words.
Ugly yours, with pestilence,
Armel
PS- rigid brain is the first step before rigid body
=====================================================
Subject: DDM program update 1.92
Date: Sun, 16 Oct 2011 20:41:12 -0700 (PDT)
From: Leonid Solovyov <l_solov...@yahoo.com>
To: rietveld_l@ill.fr
Dear Colleagues,
The DDM program update 1.92 with some minor bugs fixed is available at
http://sites.google.com/site/ddmsuite/
and
http://l-solovyov.narod.ru/ddm.html
The folder EXAMPLES\H-atoms\ now contains 15 instances of unconstrained
refinement of H-atoms from XRPD data of various quality and complexity.
A good illustration to the recent SDPD discussion on H-atoms and restraints
is the structure of C7H6ClN3O4S2 that was refined previously by a
restrained Rietveld using a combination of XRD and neutron data [Acta
Cryst. B (2008) 101]. By DDM it is refined from XRD data solely without
restraints including 6 independent H-atoms
[EXAMPLES\H-atoms\C7H6ClN3O4S2.ddm]. In the alternations of C-C and C-N
distances and angles the alternations of singe and double bonds is
correctly reproduced.
Apparently, H-atoms are not a plague and a curse, but the extensive use of
restraints is a real disease of powder diffraction. Beside all other
consequences, this pestilence diminishes the value of the method giving it
a reputation of a speculative technique.
Don't restrain, be free!
Leonid
*******************************************************
Leonid A. Solovyov
Institute of Chemistry and Chemical Technology
660049, K. Marx 42, Krasnoyarsk, Russia
http://sites.google.com/site/solovyovleonid
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