Coming back to XRD business, I feel grateful to J Bergmann

In the past decade, I wrote many critiques and proses on daily stuff.  But last week, my son said I could be the another Khan after I posted a video about Khan's Academy.  That was quite encouraging to me.  Maybe I should jot down what I do to make a living and hope this may help one or two young guys.

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Back to x-ray diffraction (XRD) from log interpretation, I have to twist the mind again on atomic position, structural factor, etc., again. In the past, I tried different Rietveld software, and I liked and still like BGMN the most.  Go to BGMN.de to find the nice things about the software.

Ufer et al 2012 talk about the 1D oriented simulation, and he summarizes the nice features of BGMN.

"BGMN contains an interpreter language which allows the definition of additional functions and parameters . The manipulation of the complex structure factors o f multiple layer structures within a single unit cell, the so-called sub-phases, is also possible. The use of an interpreter language allows a very flexible and transparent formulation without the necessity of hard coding. A super-cell approach was used to calculate the structure factors of these sub-phases periodically in the a and b directions and aperiodically in the c direction. "

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Unfortunately the author of the software, a genius in my opnion, passed away a few years back at an early age.  here is what his colleague said about him (http://www.iucr.org/resources/commissions/powder-diffraction/?a=41899)

Joerg Bergmann (1956-2010)_____________
"Joerg Bergmann studied physics in Dresden and in 1984 he presented his Ph.D thesis with the translated title "Contributions to evaluation and experimental design on X-ray powder diffraction" (http://www.bgmn.de/download/thesis.pdf).

Joerg was an exceptionally gifted mathematician.  He developed a solution for convolution-based peak profile modeling, which was integrated in a peak search program and combined with options for optimized measuring strategies.  Unfortunately, these results could not be published before the German reunification, at the EPDIC 1 in Munich (Querner et al., 1991).

Motivated by colleagues and friends, Joerg started development of a Rietveld program based on his "fundamental parameter" peak shape model in the early 90s.  I was as an inexperienced user of DBWS and was shocked when I first tested Joerg's software in 1993.  Some mysterious things happened, and the expected results were all written in the results file.  I suspected there were some dirty tricks or that some hidden parameters were fixed, but the great convergence behavior could be consistently reproduced.  This high level performance remains as one of the fascinating characteristics of BGMN to date.

Despite his poor health, Joerg worked tirelessly on the BGMN program as a private project and hobby without significant institutional support.  There are numerous impressive results and publications obtained with Joerg's software that have been noticed by the community including the IUCr indexing round robin (http://sdpd.univ-lemans.fr/sdpdrr2/sdpdrr2-CPD.pdf) and the CMS Reynolds Cup in quantitative mineral analysis (http://www.clays.org/SOCIETY%20AWARDS/RCresults.html).

Joerg's BGMN website (http://www.bgmn.de/methods.html#cite) also contributed to his reputation in the community of crystallographers and X-ray powder diffractionists and unselfishly provided valuable and practical information to people working in the field.

Joerg was known as a great personality, open in discussions and helpful in solving any scientific problems.  Sometimes it was hard to follow his highly technical thoughts, but he patiently answered any questions.  He was impressively fast at fixing bugs and implementing new features of his software that were related to someones individual scientific problem. 

Outside the scientific world he loved singing in the University chorus, hiking, and cooking exclusive meals. Joerg was also a passionate photographer and artist.  Some of his photos and computer graphics can be seen here http://www.jbergmann.de/.  Joerg's awareness about his unstable health allowed him to live intensely with the time he had and share the beauty and passion in his life with his beloved wife Anne.

Joerg Bergmann will be sorely missed by friends and colleagues in Germany and around the world.

Reinhard Kleeberg, Freiberg, Germany (October 2010)"

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I feel so privileged to talk about his software.  My last communication with the him was in 2009, a few month after I went into log analysis.  (I don't have a Dr. in the title). 

On Wednesday, July 1, 2009 12:15 AM, Joerg Bergmann <email@jbergmann.de> wrote:
Dr. Zhang:

I have added right now that function to BGMN.
It was for optimization purposes in conjunction
with the new function F(phi...) as a core of an
numerical integration (function cintegral).
The name of the new function is T2, the same has been
doen to D and the new function is called D2.

Greetings from Dresden

Joerg

Am 03.05.2009 19:56, schrieb ji zhang:
> Dr. Bergmann:
>
>
> I have another suggestion;
> can you add more positions at the T function such as
> T(6 parameters of rotation and translation; old positions; new positions)