<div dir="ltr"><div class="gmail-ajy"><img class="gmail-ajz" id="gmail-:3me" src="https://mail.google.com/mail/u/0/images/cleardot.gif" alt=""></div><div><div><div><div><div>You can set starting_pot="file" in input to restart from an existing charge density file.<br><br>Potential
or charge density, it does not matter as the former can be derived form
the latter with minimal effort and the other way round. In fact, when
you set starting_pot="file" it is the charge density, not the potential
which is read from file!<br><br><br>The problem is that the code expects
to read a file of a certain size, while the file it finds is smaller.
This is not a huge problem in principle, as all the missing bit
correspond to higher energy plane waves, and you should just put them to
zero.<br><br></div>However, this kind of mechanism is not currently
implemented in the code, not there is any project to implement it in a
near future (as far as I know). Also, the input/output system is a bit
complicated.<br><br><br></div>If you want to have a try at implementing
this rouself you have to start from./Modules/xml_io_base.f90, subroutine
read_rho_xml (line 668 in the current development version), in the
subroutine you'll find a line<br> IF ( nr1 /= nr(1) .OR. nr2 /= nr(2) .OR. nr3 /= nr(3) ) &<br> CALL errore( 'read_rho_xml', 'dimensions do not match', 1 )<br><br></div>You
should change the code in order to have it read even in the case where
the dimensions do not match, as long as nr(1)>nr1, ..., but read in a
temporary buffer, take it to G space (with the old FFT grid, this is
the hard part), pad it with zeros to the new grid size and take back to
real space with the fine grid.<br><br></div>Not impossible, but does require some effort and some testing.<br><br></div><div>Or you could write an external tool that interpolates the charge density, honestly I do not know what is more sensible.<br></div><div><br></div>hth<br><br></div><div class="gmail_extra"><br><div class="gmail_quote">On 29 September 2016 at 12:48, Muhich Christopher <span dir="ltr"><<a href="mailto:cmuhich@ethz.ch" target="_blank">cmuhich@ethz.ch</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div link="#0563C1" vlink="#954F72" lang="EN-US">
<div>
<p class="MsoNormal">Hi everyone,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I want to run a calculation at a low fft grid spacing and then use the resulting wavefunction to start a second calculation at a higher fft spacing. Is there any way to do this?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I’ve tried reading in the old charge density but this obviously doesn’t work because the fft grids don’t match.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I’ve tried reading in the old wavefunction as the starting wavefucntion, but this just collapse because atomic charge density is used as a starting point.
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks<u></u><u></u></p>
<p class="MsoNormal">Chris<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Christopher Muhich, PhD<u></u><u></u></p>
<p class="MsoNormal">ETH Zurich<u></u><u></u></p>
</div>
</div>
<br>______________________________<wbr>_________________<br>
Pw_forum mailing list<br>
<a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>
<a href="http://pwscf.org/mailman/listinfo/pw_forum" rel="noreferrer" target="_blank">http://pwscf.org/mailman/<wbr>listinfo/pw_forum</a><br></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div>Dr. Lorenzo Paulatto </div><div>IdR @ IMPMC -- CNRS & Université Paris 6</div><div>phone: +33 (0)1 44275 084 / skype: paulatz</div><div>www: <a href="http://www-int.impmc.upmc.fr/~paulatto/" target="_blank">http://www-int.impmc.upmc.fr/~paulatto/</a></div><div>mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05</div></div>
</div>