Hi Duy Le,<br><br>Thanks for the idea. Tried it, and this is what I got:<br><br>Imposed Magnetization | Total Energy (Hartree)<br>5.0<br>5.2<br>5.4<br>5.6 -55.527688685<br>5.8 -55.533921200<br>6.0 -55.540351250<br>
6.2 -55.540980910<br>6.4 -55.541296415<br>6.6 <br>6.8 <br>7.0 <br>7.2 <br><br>Values in blank are simulations that didn't execute, with the following error message:<br><br>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>
task # 0<br> from set_nelup_neldw : error # 2<br> tot_magnetization is inconsistent with total number of electrons <br> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>
<br>So two interesting facts appeared here:<br><br>1 - The energy minimum does not converge to 6, as it should do;<br>2 - When an unconstrained magnetization is used, the magnetization converges to a value around 6.82. However, If I try to impose this value as a fixed magnetization from start, pw.x won't even begin the calculation. Weird, isn't it?<br>
<br>I'm posting below a sample input file used for this battery of tests. I've used a smaller cell size here to speed things up a little. If celldm(1) is increased say to 40 instead of 25, you'll get a change in magnetic moment of about 0.05 mB. This is probably irrelevant as far as finding the cause of these results is concerned.<br>
<br>Any other suggestions, just tell me; I'll try it and report back.<br><br><br>======================<br> &CONTROL<br> calculation = 'scf' ,<br> restart_mode = 'from_scratch' ,<br>
wf_collect = .true. ,<br> outdir = './output' ,<br> pseudo_dir = '../pseudo/' ,<br> prefix = 'fe' ,<br> etot_conv_thr = 1.0D-9 ,<br>
forc_conv_thr = 1.0D-6 ,<br> tstress = .true. ,<br> tprnfor = .true. ,<br> /<br> &SYSTEM<br> ibrav = 1,<br> celldm(1) = 25,<br>
nat = 2,<br> ntyp = 1,<br> ecutwfc = 100 ,<br> ecutrho = 300 ,<br> occupations = 'smearing' ,<br> degauss = 0.005 ,<br>
smearing = 'methfessel-paxton' ,<br> nspin = 2 ,<br> starting_magnetization(1) = 1.0,<br> tot_magnetization = 6.0 ,<br> /<br> &ELECTRONS<br> conv_thr = 1.0e-9 ,<br>
mixing_beta = 0.7 ,I<br> diagonalization = 'david' ,<br> /<br>ATOMIC_SPECIES<br> Fe 58.69000 Fe.pbe-nd-rrkjus.UPF <br>ATOMIC_POSITIONS angstrom <br> Fe 0.000000000 0.000000000 0.000000000 <br>
Fe 2.048000000 0.000000000 0.000000000 <br>K_POINTS automatic <br> 1 1 1 1 1 1 <br>======================<br><br><br>Giovani <br><br><br><br><br><br><br><br><div class="gmail_quote">2011/2/13 Duy Le <span dir="ltr"><<a href="mailto:ttduyle@gmail.com" target="_blank">ttduyle@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">You should be able to fix magneticmoment of system at the desired<br>
value (say 6, 6.5, 7) to see which one give you the lowest energy.<br>
--------------------------------------------------<br>
Duy Le<br>
PhD Student<br>
Department of Physics<br>
University of Central Florida.<br>
<br>
"Men don't need hand to do things"<br>
<div><div></div><div><br>
<br>
<br>
On Sun, Feb 13, 2011 at 1:16 AM, Giovani Faccin<br>
<<a href="mailto:faccin.giovani@gmail.com" target="_blank">faccin.giovani@gmail.com</a>> wrote:<br>
> Dear Paolo,<br>
><br>
> Thanks for the reply.<br>
><br>
> Just to make sure that the simulation cell size is not an issue (so that the<br>
> system is really finite), I've tested different possibilities, including<br>
> some quite big cells. Still, after a certain size the value of the<br>
> magnetization is converging to 6.82 instead of the expected 6.<br>
><br>
> So something else is causing this. Unfortunately I've got no clue as to what<br>
> could it be.<br>
><br>
> Should it be of any help, this is my input file:<br>
><br>
><br>
> &CONTROL<br>
> calculation = 'scf' ,<br>
> restart_mode = 'from_scratch' ,<br>
> wf_collect = .true. ,<br>
> outdir = './output' ,<br>
> pseudo_dir = '../pseudo/' ,<br>
> prefix = 'fe' ,<br>
> etot_conv_thr = 1.0D-9 ,<br>
> forc_conv_thr = 1.0D-6 ,<br>
> tstress = .true. ,<br>
> tprnfor = .true. ,<br>
> /<br>
> &SYSTEM<br>
> ibrav = 1,<br>
> celldm(1) = 43,<br>
> nat = 2,<br>
> ntyp = 1,<br>
> ecutwfc = 100 ,<br>
> ecutrho = 300 ,<br>
> occupations = 'smearing' ,<br>
> degauss = 0.02 ,<br>
> smearing = 'methfessel-paxton' ,<br>
> nspin = 2 ,<br>
> starting_magnetization(1) = 1.0,<br>
> /<br>
> &ELECTRONS<br>
> conv_thr = 1.0e-9 ,<br>
> mixing_beta = 0.7 ,<br>
> diagonalization = 'david' ,<br>
> /<br>
> ATOMIC_SPECIES<br>
> Fe 58.69000 Fe.pbe-nd-rrkjus.UPF<br>
> ATOMIC_POSITIONS angstrom<br>
> Fe 0.000000000 0.000000000 0.000000000<br>
> Fe 2.047510 0.000000000 0.000000000<br>
> K_POINTS automatic<br>
> 1 1 1 1 1 1<br>
><br>
> Any suggestions are highly welcome.<br>
><br>
> Giovani<br>
><br>
><br>
> 2011/2/12 Paolo Giannozzi <<a href="mailto:giannozz@democritos.it" target="_blank">giannozz@democritos.it</a>><br>
>><br>
>> On Feb 11, 2011, at 17:09 , Giovani Faccin wrote:<br>
>><br>
>> > My question: shouldn't those numbers be integers?<br>
>><br>
>> only in finite systems, if you neglect spin-orbit.<br>
>><br>
>> P.<br>
>> ---<br>
>> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,<br>
>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>
>> Phone +39-0432-558216, fax +39-0432-558222<br>
>><br>
>><br>
>><br>
>><br>
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><br>
><br>
><br>
> --<br>
> Giovani<br>
><br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Giovani<br>