<html><head></head><body><div style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;">I would like to join this discussion and have two queries!<br><br>I finished some scf with - <g class="gr_ gr_2934 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del multiReplace" id="2934" data-gr-id="2934">fc</g> 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><br>In UG, it is mentioned that "TOLF: force tolerance, geometry optimization will stop when all forces are below TOLF."<br><br>In my case, TOLF value is 5 while - <g class="gr_ gr_2958 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del multiReplace" id="2958" data-gr-id="2958">fc</g> is 0.1 and total forces on the system <g class="gr_ gr_2955 gr-alert gr_gramm gr_inline_cards gr_run_anim Grammar multiReplace" id="2955" data-gr-id="2955">is</g> "4.598435 mRy/<g class="gr_ gr_2957 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del multiReplace" id="2957" data-gr-id="2957">bohr</g>. 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/<g class="gr_ gr_2959 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del multiReplace" id="2959" data-gr-id="2959">bohr</g>).<br><br><br>My question is can we use the same value for TOLF and -<g class="gr_ gr_2936 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del multiReplace" id="2936" data-gr-id="2936">fc</g>? i.e. 0.1 .<br><br><div>I have an additional question regarding a number of k-points:</div><div><br></div>The pristine unit cell (225 SG has 3 non-equivalent atoms). Its P-cell is having 12 non-equivalent atoms. <br><br><div>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.</div><div><br></div><div>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!<br></div><div><br></div><div>I know the basic relation between cell dimension and mesh size, <g class="gr_ gr_2938 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling" id="2938" data-gr-id="2938">nxnxn</g> 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.</div><div><br></div><div>In my bulk optimization, I used 12 12 12 mesh (for 3 non-equivalent atoms and total 9 atoms in 225 SG cell).</div><div><br></div><div>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)?</div><div><br></div><div>What should be the mesh size for the cases (from 2x22x2 supercell) with atoms 96, 72, 184 and 184?</div><div><br></div><div>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).<br></div><div><br></div><div>Hope, I explained my query nicely!</div><div><br></div> <br>Regards<br><br>Chin S.<br><br><br>On Friday 26 January 2018, 8:55:18 PM IST, Peter Blaha <pblaha@theochem.tuwien.ac.at> wrote: <br><br><br><br>Yes, of course for phonon calculations you have first to optimize <g class="gr_ gr_2973 gr-alert gr_gramm gr_inline_cards gr_run_anim Style multiReplace" id="2973" data-gr-id="2973">the </g><br><g class="gr_ gr_2973 gr-alert gr_gramm gr_inline_cards gr_disable_anim_appear Style multiReplace" id="2973" data-gr-id="2973">structure</g>. And for that, TOLF should be reduced, because for phonons you <br>should start with a structure which has "zero" (typically 0.1 to 0.01) <br>forces.<br><g class="gr_ gr_2949 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling" id="2949" data-gr-id="2949">tolf</g> tells the code when to stop moving atoms.<br>-<g class="gr_ gr_2950 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del multiReplace" id="2950" data-gr-id="2950">fc</g> <g class="gr_ gr_2971 gr-alert gr_gramm gr_inline_cards gr_run_anim Style multiReplace" id="2971" data-gr-id="2971">xx tells</g> the code to stop the scf when forces are converged to xx mRy.<br><br><br>On 01/26/2018 02:30 PM, Luis Ogando wrote:<br>> Dear Wien2k community,<br>> <br></div></body></html>