<html><head></head><body><div style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><div></div>
<div><br></div><div>Dear Sir, I got the point about <g class="gr_ gr_88 gr-alert gr_spell gr_inline_cards gr_disable_anim_appear ContextualSpelling" id="88" data-gr-id="88">tolf</g>. I am doing some test and will update by tomorrow in a fresh thread.</div><div>I will see the mesh size issue again depending on NOE and will see how I could understand.</div><div><br></div><div>Regards</div><div><br></div><div>Chin<br></div><div><br></div><div><br></div>
<div id="yahoo_quoted_7454645197" class="yahoo_quoted">
<div style="font-family:'Helvetica Neue', Helvetica, Arial, sans-serif;font-size:13px;color:#26282a;">
<div>
On Saturday 27 January 2018, 12:29:51 AM IST, Stefaan Cottenier <Stefaan.Cottenier@UGent.be> wrote:
</div>
<div><br></div>
<div><br></div>
<div><div id="yiv8119306803"><style>#yiv8119306803 #yiv8119306803 --
_filtered #yiv8119306803 {font-family:Helvetica;panose-1:2 11 6 4 2 2 2 2 2 4;}
_filtered #yiv8119306803 {panose-1:2 4 5 3 5 4 6 3 2 4;}
_filtered #yiv8119306803 {font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;}
#yiv8119306803
#yiv8119306803 p.yiv8119306803MsoNormal, #yiv8119306803 li.yiv8119306803MsoNormal, #yiv8119306803 div.yiv8119306803MsoNormal
{margin:0cm;margin-bottom:.0001pt;font-size:11.0pt;}
#yiv8119306803 a:link, #yiv8119306803 span.yiv8119306803MsoHyperlink
{color:#0563C1;text-decoration:underline;}
#yiv8119306803 a:visited, #yiv8119306803 span.yiv8119306803MsoHyperlinkFollowed
{color:#954F72;text-decoration:underline;}
#yiv8119306803 p.yiv8119306803msonormal0, #yiv8119306803 li.yiv8119306803msonormal0, #yiv8119306803 div.yiv8119306803msonormal0
{margin-right:0cm;margin-left:0cm;font-size:11.0pt;}
#yiv8119306803 span.yiv8119306803E-mailStijl19
{color:windowtext;}
#yiv8119306803 .yiv8119306803MsoChpDefault
{font-size:10.0pt;}
_filtered #yiv8119306803 {margin:70.85pt 70.85pt 70.85pt 70.85pt;}
#yiv8119306803 div.yiv8119306803WordSection1
{}
#yiv8119306803 </style><div>
<div class="yiv8119306803WordSection1">
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US">TOLF is needed only when you are creating your initial, entirely optimized cell that will be the start for your phonon calculations. It is not used during the force calculation in the
distorted cells.</span></p>
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US"> </span></p>
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US">-fc 0.1 is used as a stopping criterium during one scf cycle: the scf cycle will stop when forces do not change any longer by more than 0.1.</span></p>
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US"> </span></p>
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US">-fc must be smaller than TOLF, rule of thumb 3-10 times smaller. Imagine the opposite, say -fc 1.0 and TOLF=0.1 : the scf-cycle will stop as soon as forces vary within 1.0 only, but
the position optimization would stop only if forces are below 0.1. If that would happen, it would be by chance only.</span></p>
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US"> </span></p>
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US">About the counting in your distorted cells: do you report the total number of atoms, or the inequivalent number of atoms? For more unambiguous counting, it’s easier to count the number
of electrons (NE in case.in2). Does it make more sense that way? If you have 2 times more electrons, the total number of k-points can be divided by 2 (e.g. from -numk 1000 to -numk 500), without having to care about divisions per axis.</span></p>
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US"> </span></p>
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US">Stefaan</span></p>
<p class="yiv8119306803MsoNormal"><span style="" lang="EN-US"> </span></p>
<p class="yiv8119306803MsoNormal"><a rel="nofollow" shape="rect" name="_MailEndCompose"><span style="" lang="EN-US"> </span></a></p>
<span style=""></span>
<div class="yiv8119306803yqt2417294860" id="yiv8119306803yqt37339"><div style="border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt;">
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm;">
<p class="yiv8119306803MsoNormal"><b><span lang="NL">Van:</span></b><span lang="NL"> Wien [mailto:wien-bounces@zeus.theochem.tuwien.ac.at]
<b>Namens </b>chin Sabsu<br clear="none">
<b>Verzonden:</b> vrijdag 26 januari 2018 17:11<br clear="none">
<b>Aan:</b> wien@zeus.theochem.tuwien.ac.at<br clear="none">
<b>Onderwerp:</b> Re: [Wien] Optimization convergence for phonon calculations.</span></p>
</div>
</div>
<p class="yiv8119306803MsoNormal"> </p>
<div>
<p class="yiv8119306803MsoNormal" style="margin-bottom:12.0pt;"><span style="font-size:12.0pt;">I would like to join this discussion and have two queries!<br clear="none">
<br clear="none">
I finished some scf with - fc 0.1. Previously I was not aware of TOLF but now I see the importance of TOLF factor. Now I see that TOLF is defined in case.inM.<br clear="none">
<br clear="none">
In UG, it is mentioned that "TOLF: force tolerance, geometry optimization will stop when all forces are below TOLF."<br clear="none">
<br clear="none">
In my case, TOLF value is 5 while - fc is 0.1 and total forces on the system is "4.598435 mRy/bohr. So according to Peter's reply, this scf calculation is not good for phonon calculations and the forces must be small as much as we can get (0.1mRy/bohr).<br clear="none">
<br clear="none">
<br clear="none">
My question is can we use the same value for TOLF and -fc? i.e. 0.1 .</span></p>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;">I have an additional question regarding a number of k-points:</span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"> </span></p>
</div>
<p class="yiv8119306803MsoNormal" style="margin-bottom:12.0pt;"><span style="font-size:12.0pt;">The pristine unit cell (225 SG has 3 non-equivalent atoms). Its P-cell is having 12 non-equivalent atoms.
</span></p>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;">If I create the distorted structure for Phonopy by 1x1x1 cell then the atoms become 16, 15, 28 and 28 with no change in lattice dimension.</span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"> </span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;">When I create the distorted structure for by 2x2x2 cell then the atoms become 96, 72, 184 and 184 nonequivalent atoms in four *struct_00* files and lattice parameters are
doubled which is obviously should be!</span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"> </span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;">I know the basic relation between cell dimension and mesh size, nxnxn supercell Kx/n, Ky/n, Kz/n mesh size, but here I stuck and not able to pick to suitable mesh size which
reduces my computational power.</span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"> </span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;">In my bulk optimization, I used 12 12 12 mesh (for 3 non-equivalent atoms and total 9 atoms in 225 SG cell).</span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"> </span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;">According to your expertise what should be the mesh size for the structure created by 1x1x1 supercell (four distorted structures with 16, 15, 28 and 28 atoms)?</span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"> </span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;">What should be the mesh size for the cases (from 2x22x2 supercell) with atoms 96, 72, 184 and 184?</span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"> </span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;">Why I asked this question on mesh size is: because with 6x6x6 mesh size and RKmax 6 one scf cycle is not completed even after two hrs on 8 cores (for a single case).</span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"> </span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;">Hope, I explained my query nicely!</span></p>
</div>
<div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"> </span></p>
</div>
<p class="yiv8119306803MsoNormal"><span style="font-size:12.0pt;"><br clear="none">
Regards<br clear="none">
<br clear="none">
Chin S.<br clear="none">
<br clear="none">
<br clear="none">
On Friday 26 January 2018, 8:55:18 PM IST, Peter Blaha <<a rel="nofollow" shape="rect" ymailto="mailto:pblaha@theochem.tuwien.ac.at" target="_blank" href="mailto:pblaha@theochem.tuwien.ac.at">pblaha@theochem.tuwien.ac.at</a>> wrote:
<br clear="none">
<br clear="none">
<br clear="none">
<br clear="none">
Yes, of course for phonon calculations you have first to optimize the <br clear="none">
structure. And for that, TOLF should be reduced, because for phonons you <br clear="none">
should start with a structure which has "zero" (typically 0.1 to 0.01) <br clear="none">
forces.<br clear="none">
tolf tells the code when to stop moving atoms.<br clear="none">
-fc xx tells the code to stop the scf when forces are converged to xx mRy.<br clear="none">
<br clear="none">
<br clear="none">
On 01/26/2018 02:30 PM, Luis Ogando wrote:<br clear="none">
> Dear Wien2k community,<br clear="none">
> </span></p>
</div>
</div></div>
</div>
</div></div><div class="yqt2417294860" id="yqt49761">_______________________________________________<br clear="none">Wien mailing list<br clear="none"><a shape="rect" ymailto="mailto:Wien@zeus.theochem.tuwien.ac.at" href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a><br clear="none"><a shape="rect" href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien" target="_blank">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a><br clear="none">SEARCH the MAILING-LIST at: <a shape="rect" href="http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html" target="_blank">http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html</a><br clear="none"></div></div>
</div>
</div></div></body></html>