<div dir="ltr"><div><div><div><div>Dear QE exparts, <br><br><br></div> How to get rid of the small unit cell problem? <br></div> When it is a pure system, Wycoff positions with Atomic positions card set at alat works. So, is there any definite procedure to give the position of the atoms in the system when I am doping in the system?<br><br></div> Thanking you,<br></div> Sayan Chaudhuri<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Dec 9, 2016 at 7:07 PM, Lorenzo Paulatto <span dir="ltr"><<a href="mailto:lorenzo.paulatto@impmc.upmc.fr" target="_blank">lorenzo.paulatto@impmc.upmc.fr</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">It may be difficult to converge LDA+U calculations in general, starting with<br>
initial magnetizations that aren't absurd may help<br>
<br>
hth<br>
<div class="HOEnZb"><div class="h5"><br>
On Friday, December 9, 2016 5:29:01 PM CET Максим Арсентьев wrote:<br>
> Dear Lorenzo,<br>
><br>
> I have the same problem - cannot achieve SCF convergence. I use higher<br>
> ecutwfc = 39.0, ecutrho = 300 but not coverging.<br>
><br>
> Regards, Maxim Arsentev.<br>
><br>
> 2016-12-09 12:52 GMT+04:00 Lorenzo Paulatto <<a href="mailto:lorenzo.paulatto@impmc.upmc.fr">lorenzo.paulatto@impmc.upmc.<wbr>fr</a>><br>
> > Dear Sayan,<br>
> > it looks to me like your unit cell is too small, the atoms are all crumped<br>
> > together. Please note that celldm(1) is specified in bohr atomic units.<br>
> ><br>
> > Also:<br>
> > 1. a cutoff of 30Ry is probably very small for BHS pseudopotentials<br>
> > 2. ecutrho=default (4*ecutwfc ) is probably not enough for all the<br>
> > ultrasoft<br>
> > pseudopotentials you are using<br>
> ><br>
> > I would recommend you first spend some time reproducin the single-element<br>
> > metal, and once you can correctly reproduce geometry, band structure,<br>
> > physical<br>
> > properties, you move to simulating the alloy.<br>
> ><br>
> > HTH<br>
> ><br>
> > On Friday, December 9, 2016 1:59:44 PM CET sayan chaudhuri wrote:<br>
> > > Hi,<br>
> > ><br>
> > > I am running QE self - consistently for my heusler alloy(Fe2TiSn)<br>
> > ><br>
> > > system, where 25% of Sn were replaced by Sb. But after 800 iterations<br>
> > > and<br>
> > > almost 3 hours of running also still it is not converged.<br>
> > > The code I am using is added bellow. Please tell me what is the source<br>
> > > of<br>
> > > error.<br>
> > ><br>
> > > Thanking you,<br>
> > ><br>
> > > Sayan Chaudhuri<br>
> > ><br>
> > > *&control prefix='fts', calculation = 'scf', verbosity =<br>
> > > 'low', pseudo_dir = '/home/ltp/Desktop/espresso-5.<wbr>4.0/pseudo',<br>
> > > outdir = './tmp', / &system ibrav=2 celldm(1)=11.43,<br>
> > > nat=16, ntyp=4, nspin=2, ecutwfc=30.0,<br>
> > > starting_magnetization(1) = 0.0, starting_magnetization(2) = 0.0,<br>
> > > starting_magnetization(3) = 0.5, starting_magnetization(3) = 0.0,<br>
> > > occupations='tetrahedra', / &electrons electron_maxstep = 3000,<br>
> > > diagonalization = 'david', mixing_mode = 'plain', conv_thr = 1e-8,<br>
> > > mixing_beta=0.1, /ATOMIC_SPECIES Sb 121.76 Sb.pz-bhs.UPF Sn<br>
> > > 118.71 Sn.pz-dn-rrkjus_psl.0.2.UPF Fe 55.845 Fe.pz-sp-van_ak.UPF<br>
> > > Ti 47.867 Ti.pz-sp-van.UPFATOMIC_<wbr>POSITIONS {crystal} Sb<br>
> > > 0.000000000 0.000000000 0.000000000 Sn<br>
> > > 0.000000000 0.500000000 0.500000000 Sn<br>
> > > 0.500000000 0.000000000 0.500000000 Sb<br>
> > > 0.500000000 0.500000000 0.000000000 Fe<br>
> > > 0.250000000 0.250000000 0.250000000 Fe<br>
> > > 0.750000000 0.750000000 0.750000000 Fe<br>
> > > 0.750000000 0.750000000 0.250000000 Fe<br>
> > > 0.250000000 0.250000000 0.750000000 Fe<br>
> > > 0.750000000 0.250000000 0.750000000 Fe<br>
> > > 0.250000000 0.750000000 0.250000000 Fe<br>
> > > 0.250000000 0.750000000 0.750000000 Fe<br>
> > > 0.750000000 0.250000000 0.250000000 Ti<br>
> > > 0.500000000 0.500000000 0.500000000 Ti<br>
> > > 0.500000000 0.000000000 0.000000000 Ti<br>
> > > 0.000000000 0.500000000 0.000000000 Ti<br>
> > > 0.000000000 0.000000000 0.500000000 K_POINTS {automatic}<br>
> > > 2 2 2 0 0 0*<br>
> ><br>
> > --<br>
> > Dr. Lorenzo Paulatto<br>
> > IdR @ IMPMC -- CNRS & Université Paris 6<br>
> > phone: +33 (0)1 44275 084 / skype: paulatz<br>
> > www: <a href="http://www-int.impmc.upmc.fr/~paulatto/" rel="noreferrer" target="_blank">http://www-int.impmc.upmc.fr/~<wbr>paulatto/</a><br>
> > mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05<br>
> ><br>
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<br>
<br>
--<br>
Dr. Lorenzo Paulatto<br>
IdR @ IMPMC -- CNRS & Université Paris 6<br>
phone: +33 (0)1 44275 084 / skype: paulatz<br>
www: <a href="http://www-int.impmc.upmc.fr/~paulatto/" rel="noreferrer" target="_blank">http://www-int.impmc.upmc.fr/~<wbr>paulatto/</a><br>
mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05<br>
<br>
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