<div dir="auto"><div>Dear Paolo,<div dir="auto"><br></div><div dir="auto">I can make 8:00 am (3:00 pm), although I need to be at a department retreat at 9:00 am.<br><br><div data-smartmail="gmail_signature" dir="auto">---<br>Prof Laurence Marks<br>"Research is to see what everyone else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi<br><a href="http://www.numis.northwestern.edu" target="_blank" rel="noreferrer">www.numis.northwestern.edu</a></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Sep 22, 2019, 14:58 Paolo Giannozzi <<a href="mailto:p.giannozzi@gmail.com" target="_blank" rel="noreferrer">p.giannozzi@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Dear Laurence, it is definitely a good idea that fits perfectly into the current efforts towards modularization. The refactoring of the charge mixing algorithm used in QE into a library is one of the possible activities of the MaX - Materials at the Exascale Centre of Excellence. There will be an online meeting of the QE developers tomorrow (Monday 23) at 3pm Trieste time (should be 8am for you): are you by any chance able to join? <br></div><div><br></div><div>Paolo</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Sep 20, 2019 at 10:46 PM Laurence Marks <<a href="mailto:laurence.marks@gmail.com" rel="noreferrer noreferrer" target="_blank">laurence.marks@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif;color:rgb(0,0,0)"><p class="MsoNormal" style="margin:0cm 0cm 8pt;line-height:107%;font-size:11pt;font-family:Calibri,sans-serif">I would defend the perhaps bold statement that the mixer in
Wien2k is state of the art. It has sophisticated implicit and explicit trust
region controls (not all details published yet), so needs essentially no user input. It is also fast, and the
algorithm which does simultaneous density and atomic optimization is powerful.</p>
<p class="MsoNormal" style="margin:0cm 0cm 8pt;line-height:107%;font-size:11pt;font-family:Calibri,sans-serif">That said, it is also complicated. Rebuilding it from scratch
for another DFT code would be a significant task.</p>
<p class="MsoNormal" style="margin:0cm 0cm 8pt;line-height:107%;font-size:11pt;font-family:Calibri,sans-serif">In addition, maintaining it in Wien2k would not be trivial
if I stopped work. While I am not retiring tomorrow, I also won’t keep working
into my old age.</p>
<p class="MsoNormal" style="margin:0cm 0cm 8pt;line-height:107%;font-size:11pt;font-family:Calibri,sans-serif">What to do? </p><p class="MsoNormal" style="margin:0cm 0cm 8pt;line-height:107%;font-size:11pt;font-family:Calibri,sans-serif">One thought is to create OpenMix. This would be
an open source (e.g. GitHub) code which includes the trust region controls of
the mixer in Wien2k with the existing MSEC, MSR1 algorithms as well as others
such as DIIS. Build a core with hooks so any and every DFT
code can directly use the algorithms via either reverse or forward
communication.</p>
<p class="MsoNormal" style="margin:0cm 0cm 8pt;line-height:107%;font-size:11pt;font-family:Calibri,sans-serif">I am pondering this, and would be interested to know if you
think it would be a good idea and would be supportive.</p></div><div><br></div>-- <br><div dir="ltr" class="m_-222764810380344820m_-6220827086746908294gmail-m_-8391394964526894988gmail_signature"><div dir="ltr">Professor Laurence Marks<br>Department of Materials Science and Engineering<br>Northwestern University<br><a href="http://www.numis.northwestern.edu/" rel="noreferrer noreferrer" target="_blank">www.numis.northwestern.edu</a><div>Corrosion in 4D: <a href="http://www.numis.northwestern.edu/MURI" rel="noreferrer noreferrer" target="_blank">www.numis.northwestern.edu/MURI</a><br>Co-Editor, Acta Cryst A<br>"Research is to see what everybody else has seen, and to think what nobody else has thought"<br>Albert Szent-Gyorgi</div></div></div></div>
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</blockquote></div><br clear="all"><br>-- <br><div dir="ltr" class="m_-222764810380344820m_-6220827086746908294gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,<br>Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>Phone +39-0432-558216, fax +39-0432-558222<br><br></div></div></div></div></div>
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