<div dir="ltr">Dear Prof. Laurence Marks Sir,<div><br></div><div> Thank you for your email.</div><div>Sir, we have obtained the following results by using the above procedure;</div><div><br></div><div>Expt. Theory</div><div>a=12.134 a=11.8071 </div><div>b= 3.87 b=3.8838</div><div>c= 11.23 c=10.9285</div><div><br></div><div>Whether these are acceptable results?</div><div><br></div><div>with regards, </div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 12 Aug 2020 at 18:53, Laurence Marks <<a href="mailto:laurence.marks@gmail.com" target="_blank">laurence.marks@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">I have an impression that you have asked before about optimization, in fact many times!<div dir="auto"><br></div><div dir="auto">A question you should ask yourself is what are you trying to achieve? DFT is not a perfect theory, and while you can improve the agreement with experiment using better (and slower) methods, in general experiment is more accurate.</div><div dir="auto"><br></div><div dir="auto">If your calculations are close to experiment, e.g. atoms at positions maybe 0.01 Angers off, that is all you can expect.</div><div dir="auto"><br></div><div dir="auto">If, for instance, the positions are 0.1 Angers off, and/or it is a metal whereas in experiment it is an insulator, then something is very wrong. No amount of lattice optimization is going to help.</div><div dir="auto"><br></div><div dir="auto">So, my question to you is are you killing defenseless electrons in a quest to overfit data, or is there a reason?<br><br><div dir="auto">_____<br>Professor Laurence Marks<br>"Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi<br><a href="http://www.numis.northwestern.edu" target="_blank">www.numis.northwestern.edu</a></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Aug 12, 2020, 08:11 shamik chakrabarti <<a href="mailto:shamik15041981@gmail.com" target="_blank">shamik15041981@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Also after obtaining the c/a optimized struct file with optimized lattice parameter & nearly optimized atomic coordinates for a hexagonal system I do a force minimization by keeping the lattice parameter intact (as obtained from c/a optimization curve). Whether this will give a wrong minima?<br><div><br></div><div>with regards,</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 12 Aug 2020 at 18:17, shamik chakrabarti <<a href="mailto:shamik15041981@gmail.com" rel="noreferrer" target="_blank">shamik15041981@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Dear Prof. Blaha,<br><div><br></div><div> I have done some calculations by keeping both lines active. What it does;</div><div>(!) It runs first runsp_lapw -ec 0.0001 for a given struct file</div><div>(2) After getting the energy convergence, it does the force minimization for the given structure & saves the successive struct files as case_i.scf for i=1,2....</div><div>(3) after getting the force optimized structure it saves the optimized struct files in case....._default.struct.</div><div><br></div><div>What I do I take the optimized struct file which is near the minima i.e, say case_coa____-5.00 _default .struct for next calculation & put the lattice parameters in this file by calculating it by hand from c/a optimized curve.</div><div><br></div><div>Is this give the wrong minimum?</div><div><br></div><div>Looking forward to your response in this regard.</div><div><br></div><div>with regards,</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 12 Aug 2020 at 17:59, Peter Blaha <<a href="mailto:pblaha@theochem.tuwien.ac.at" rel="noreferrer" target="_blank">pblaha@theochem.tuwien.ac.at</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">You certainly don't want both lines active.<br>
<br>
For a simultaneous optimization of internal coordinates, the recommended <br>
command in optimize.job is to add -min to the run-command:<br>
<br>
runsp_lapw -nlvdw -fc 1 -ec 0.001 -min<br>
<br>
An older alternative (usually not recommended) is:<br>
<br>
min -I -j "runsp_lapw -nlvdw -I -fc 1.0 -i 40 "<br>
<br>
<br>
On 8/12/20 11:03 AM, shamik chakrabarti wrote:<br>
> Dear Wien2k users,<br>
> I have edited the optimized.job by <br>
> uncommenting the following two lines for running simultaneous <br>
> optimization of atomic coordinates with a,b,c:<br>
> <br>
> runsp_lapw -nlvdw -ec 0.0001<br>
> <br>
> min -I -j "runsp_lapw -nlvdw -I -fc 1.0 -i 40 "<br>
> <br>
> Is this method is correct?<br>
> <br>
> Looking forward to hearing from you.<br>
> <br>
> Thanks in advance<br>
> <br>
> with regards,<br>
> <br>
> -- <br>
> Dr. Shamik Chakrabarti<br>
> Research Fellow<br>
> Department of Physics<br>
> Indian Institute of Technology Patna<br>
> Bihta-801103<br>
> Patna<br>
> Bihar, India<br>
> <br>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div style="font-size:small">Dr. Shamik Chakrabarti</div><div style="font-size:small">Research Fellow </div><div style="font-size:small">Department of Physics</div><div style="font-size:small">Indian Institute of Technology Patna</div><div style="font-size:small">Bihta-801103</div><div style="font-size:small">Patna</div><div style="font-size:small">Bihar, India</div></div></div></div></div></div></div></div>
</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div style="font-size:small">Dr. Shamik Chakrabarti</div><div style="font-size:small">Research Fellow </div><div style="font-size:small">Department of Physics</div><div style="font-size:small">Indian Institute of Technology Patna</div><div style="font-size:small">Bihta-801103</div><div style="font-size:small">Patna</div><div style="font-size:small">Bihar, India</div></div></div></div></div></div></div></div>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div style="font-size:small">Dr. Shamik Chakrabarti</div><div style="font-size:small">Research Fellow </div><div style="font-size:small">Department of Physics</div><div style="font-size:small">Indian Institute of Technology Patna</div><div style="font-size:small">Bihta-801103</div><div style="font-size:small">Patna</div><div style="font-size:small">Bihar, India</div></div></div></div></div></div></div></div>