Dear Prof. Laurence Marks,<div><br></div><div> I have constrained some fixed positions for keeping them intact due to the following reason:</div><div><br></div><div>(i) I am doing a calculation which is a primitive supercell generated from the original unit cell having a particular space group.</div>
<div>(ii) Similar type of calculation on a different material (by generating primitive space group) showed earlier that if the original structure has a coordinate say (0.5, 0, 0) after force minimization with the primitive space group the optimized coordinates eventually turned out to be (0.4995, 0.9998, 0.9997) and hence we have again came back to our original position (0.5, 0, 0). Hence, optimizing these fixed coordinates seems to be an wastage of computational time while only varying the variable coordinates (of the primitive space group) may give the equilibrium structure in a relatively small time.</div>
<div><br></div><div>As you have mentioned, that I have not give enough information for finding out the reason behind the crash, Sir, can you please suggest me which information should I give?....as already I have given the following information:</div>
<div><br></div><div>(i) There is no error file</div><div>(ii) case.scf2up is empty (as lapw2 -c -up crashed)</div><div>(iii) I am not able to figure out any error messages from case.output2</div><div><br></div><div>Also, the initial positions for the structure has been entered carefully. The coordinates are determined from Rietveld analysis of experimental XRD which is also confronted with earlier findings. </div>
<div><br></div><div>Looking forward to your response.</div><div><br></div><div>with best regards,<br><br><div class="gmail_quote">On Thu, Aug 23, 2012 at 6:19 PM, Laurence Marks <span dir="ltr"><<a href="mailto:L-marks@northwestern.edu" target="_blank">L-marks@northwestern.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">You have misunderstood the UG. Wien2k knows about fixed positions due<br>
to symmetry and so long as you have entered your positions with<br>
precision, e.g. 0.33333333 not 0.33330000 you should not impose<br>
additional constraints yourself. In addition there is no reason to use<br>
NEW1 if you do have constraints as both PORT and MSR1a obey them.<br>
However, unless you have a very good reason I do not recommend using<br>
constraints.<br>
<br>
As to why your calculation crashed, no idea as you have not provided<br>
enough information for anyone to guess. I suspect that you have chosen<br>
inappropriate parameters and/or have a mistake in your input. Most<br>
oxides are centrosymmetric and a common mistake is to get a lower<br>
symmetry by not entering the initial positions with enough accuracy.<br>
<div class="HOEnZb"><div class="h5"><br>
On Thu, Aug 23, 2012 at 5:39 AM, shamik chakrabarti <<a href="mailto:shamikphy@gmail.com">shamikphy@gmail.com</a>> wrote:<br>
> Dear wien2k users,<br>
><br>
> I was running force minimization of a 56 atomic cell ( an oxide<br>
> material) by constraining the coordinates of elements other than oxygen as<br>
> that is the only variable parameter (other coordinates are fixed obeying<br>
> space group symmetry) in wien2k 11.1<br>
><br>
> I was using NEW1 minimization method following user guide -- "In case of<br>
> constraint calculations one should use NEW1"<br>
><br>
> Two structure files having different atomic coordinates were already<br>
> created.<br>
><br>
> while when running SCF calculation using the 3rd struct file, SCF was<br>
> aborted by mentioning the line at the 4th iteration:<br>
><br>
> > lapw2 -c -up (15:01:51) Abort<br>
> 3.348u 0.320s 0:01.61 227.3% 0+0k 0+20376io 0pf+0w<br>
> error: command /home/shamik81/WIEN2k/lapw2c uplapw2.def failed<br>
><br>
>> stop error<br>
><br>
> Another unusual thing is that the energy and charge convergence in different<br>
> iterations of this SCF cycle went on as below:<br>
><br>
> EC: .000041 CC: .0007728<br>
> EC: .00600493 CC. .0028021<br>
> EC: .002993535 CC. .0028017<br>
><br>
> There was no error file created and I haven't found any error indicated in<br>
> case.output2 (up/dn) file and case.scf2up file was empty as lapw2 got<br>
> aborted when it was just started.<br>
><br>
> Charge distance in the above SCF cycle went on as following:<br>
><br>
> :DIS : CHARGE DISTANCE ( 0.0007728 for atom 48 spin 2)<br>
> 0.0002381<br>
> :DIS : CHARGE DISTANCE ( 0.0028021 for atom 29 spin 2)<br>
> 0.0019903<br>
> :DIS : CHARGE DISTANCE ( 0.0028017 for atom 29 spin 2)<br>
> 0.0019911<br>
><br>
> We are not able to figure out what the problem is. Any response in this<br>
> regard will be very helpful for us.<br>
><br>
> with regards,<br>
><br>
> --<br>
> Shamik Chakrabarti<br>
> Senior Research Fellow<br>
> Dept. of Physics & Meteorology<br>
> Material Processing & Solid State Ionics Lab<br>
> IIT Kharagpur<br>
> Kharagpur 721302<br>
> INDIA<br>
<br>
<br>
<br>
</div></div><span class="HOEnZb"><font color="#888888">--<br>
Professor Laurence Marks<br>
Department of Materials Science and Engineering<br>
Northwestern University<br>
<a href="http://www.numis.northwestern.edu" target="_blank">www.numis.northwestern.edu</a> 1-847-491-3996<br>
"Research is to see what everybody else has seen, and to think what<br>
nobody else has thought"<br>
Albert Szent-Gyorgi<br>
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</font></span></blockquote></div><br><br clear="all"><div><br></div>-- <br>Shamik Chakrabarti<br>Senior Research Fellow<br>Dept. of Physics & Meteorology<br>Material Processing & Solid State Ionics Lab<br>IIT Kharagpur<br>
Kharagpur 721302<br>INDIA<br>
</div>