Dear Stefano,<div><br><div>Thanks for the quick reply. I think it probably best to stick with a solution inside the code. It sounds like everything is already there and my job will more akin to plumbing than algorithm testing and validation. I'll take a look at it soon. What is the proper way to submit code for review once I get that far?</div>
<div><br></div><div>Luke<div>Geophysical Laboratory</div><div>Carnegie Institution of Washington</div><div>(<a href="mailto:lshulenburger@ciw.edu">lshulenburger@ciw.edu</a>)</div><div class="gmail_quote"><br></div><div class="gmail_quote">
<br></div><div class="gmail_quote">On Sun, Feb 28, 2010 at 4:17 AM, Stefano Baroni <span dir="ltr"><<a href="mailto:baroni@sissa.it">baroni@sissa.it</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div style="word-wrap:break-word"><div>Dear Luke:</div><div><br></div>I am no longer familiar with the guts of the code, but I think this would require some coding. The problem is, the PW basis set (and the related FFT grids) slightly depends on the strain state. In variable-cell MD, this dependence is eliminated by using a "hard" cutoff that defines the PW basis set and a "smooth" one that implicitly, but continuously, eliminates some of the PWs according to the strain state. I can see two strategies that you may want to try. <div>
<br></div><div>The first would probably require you to put your hands into PW: you simply have to make the "soft" cutoff option available to static scf calculations. I believe this should be rather easy, and I will ask some of the people who know the code well to assist you if you want to try.</div>
<div><br></div><div>Second option. Do Fourier interpolation. Take the charge density / wavefunctions calculated and stored with one FFT grid and use a simple stand-alone program to calculate the fourier coefficients with respect to a different grid. Writing this simple code would not require any knowledge of the PW guts. If you want to give it a try, I can give you a few hints.</div>
<div><br></div><div>If you decide to try either one of the above two approaches, I beileve the QE developers' team would be more than glald to help and to include your contribution in a future distribution of QE.</div>
<div><br></div><div>Cheers</div><div>Stefano B</div><div><br><div><div><div></div><div class="h5"><div>On Feb 28, 2010, at 3:33 AM, Luke Shulenburger wrote:</div><br></div></div><blockquote type="cite"><div><div></div><div class="h5">
Hello,<div><br><div>I would like to calculate the ground state of a system with several different strains. As the calculations are somewhat hard to converge, I was hoping that I could re-use the density and wavefunctions from one of the calculations as starting points of the others. I know that the code does this under the hood when the geometry is changed in MD or geometry optimizations, but I cannot seem to get it to work for separate static scf calculations. Is this feature available?</div>
<div><br></div><div>Luke Shulenburger</div><div>Geophysical Laboratory</div><div>Carnegie Institution of Washington</div><div>(<a href="mailto:lshulenburger@ciw.edu" target="_blank">lshulenburger@ciw.edu</a>)</div></div>
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<div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><font size="3"><span style="font-size:12px">---</span></font></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
<font size="3"><span style="font-size:12px">Stefano Baroni - SISSA</span></font><font size="3"><span style="font-size:12px"> </span></font><font size="3"><span style="font-size:12px">&</span></font><font size="3"><span style="font-size:12px"> </span></font><font size="3"><span style="font-size:12px">DEMOCRITOS National Simulation Center - Trieste</span></font></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><font size="3"><span style="font-size:12px"><a href="http://stefano.baroni.me" target="_blank">http://stefano.baroni.me</a> [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)</span></font></div>
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<span style="font-size:14px"><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><font size="3"><span style="font-size:12px">La morale est une logique de l'action comme la logique est une morale de la pensée - Jean Piaget</span></font></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><font size="3"><span style="font-size:12px"><br></span></font></div></span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
<font size="3"><span style="font-size:12px">Please, if possible, don't</span></font><font size="3"><span style="font-size:12px"> </span></font><font size="3"><span style="font-size:12px">send me MS Word or PowerPoint attachments</span></font></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><font size="3"><span style="font-size:12px">Why? See:</span></font><font size="3"><span style="font-size:12px"> </span></font><font color="#0023E9" size="3"><span style="font-size:12px"><a href="http://www.gnu.org/philosophy/no-word-attachments.html" target="_blank">http://www.gnu.org/philosophy/no-word-attachments.html</a></span></font></div>
<div><font color="#0023E9" size="3"><span style="font-size:12px"><br></span></font></div></div></div></span><br></div></span><br></div></span><br></div></span><br></span><br>
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