On 08/13/2018 03:43 PM, Toby, Brian H. wrote:
Dear Henk,
I am not sure if this is what was intended in your commentary and e-mail,
but I read from it the point that have heard often over the years, which is that
someone is less than fully deserving of scientific credit because “s/he only
developed the software” and in particular the term "the Rietveld Method”
neglects the range of contributions from others in the scientific process. I
think this needs a response.
There is no doubt that pattern fitting /for extracting peak
intensities/ predates the 1967 and 1969 papers from Hugo Rietveld, even though
back then peak areas were most commonly estimated with a planimeter
(https://en.wikipedia.org/wiki/Planimeter — I can remember my father around then
using one for chromatography) or cutting and weighing. Likewise many people
worked on developing the parameterization that allowed quantitative modeling of
CW neutron diffraction peaks (though notably my understanding is that the
well-known Cagliotti equation is a reformulation that Hugo first published, but
credited to Cagliotti.) Van Laar sometime later contributed greatly to our
understanding of low-angle asymmetric peak broadening (but again, fairly or not,
most credit goes to Finger, Cox and Jephcoat who first released a general
purpose program, even though Eddy and David first showed that it could be
coded). I would guess that many people discussed the idea of determining
crystallographic parameters by directly fitting to a diffractogram, but Hugo
first developed an Algol code that actually implemented that concept, in a time
when tackling such a large problem with the tiny computers available those days
was an incredible achievement. If that was not enough, since Algol was not
widely used, he then rewrote his code in Fortran to make his method more available.
His Fortran code offered quite sophisticated crystallographic models,
including magnetic scattering, and allowed complex groupings of parameters.
Taking the idea of full pattern fitting from a concept to a method required
considerable innovation. As one example, Hugo invented an intensity extraction
algorithm that, as far as I am aware, is in every current program powder fitting
in current use. Hugo’s extraction method was later incorporated into the LeBail
method, when Armel came up with his smart idea to recycle those intensities.
One measure of how far ahead of the curve Hugo’s work had been is to look
at how long it took to see widespread acceptance. Around 1985, when I was first
exposed to it, it was only just becoming be used outside of a few choice labs.
Incidentally, what I used then was a code that had been passed through several
hands and modified in each, but was based on Hugo’s original Fortran
implementation. My understanding is that just about every Rietveld code that was
available through to the 1990’s, with the one exception of GSAS, contained some
of Hugo’s code.
Hugo was one of many, many people who contributed to modern powder
diffraction practice, but his solo work handed the world a tool which invented
my field — powder diffraction crystallography — and I am most respectful of
that. I cannot speak for others, but I personally will continue to use the term
Rietveld analysis to honor an accomplishment that was well ahead of its time. It
did not occur in a vacuum — little in science does, including the work of both
Newton and Einstein — but still was an incredible step forward.
Brian,
My interpretation is not that the writer of the software should have been
discredited, but that the other contributors should have been authors.
Your example of Finger, Cox, and Jephcoat is a good one. Yes, we did stand on
the shoulders of others, but I think we gave them credit in the manuscript. For
whatever reasons, none of their contributions had made it into code. By our
re-deriving the equations in a computable form, and providing a sample
implementation code, our contribution stuck. In fact, ResearchGate still reports
3 or 4 citations of the paper per month, which is remarkable for a paper
published 24 years ago.
There would have been a closer parallel if I had ignored Dave's and Andrew's
contributions to the project, and published a single-author paper! That would
not have been fair, nor was it the way I worked.
Larry
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