<div dir="ltr">Thank you Dr. Tran<div><br><div>Yes, I took only 6x6x6 k-mesh for optimization.</div><div>I will test it further for 8x8x8, 10x10x10</div><div><br></div><div><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, May 5, 2017 at 1:00 AM, <span dir="ltr"><<a href="mailto:tran@theochem.tuwien.ac.at" target="_blank">tran@theochem.tuwien.ac.at</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<br>
If the SCF calculations were done with a value for a parameter (e.g.,<br>
RKmax, number of k-points or energy convergence criteria) that was<br>
not good enough, then this may introduce some noise such that the<br>
Murnaghan EOS can not fit perfectly the data and, therefore,<br>
leads to an optimised lattice parameter that depends on the chosen<br>
volumes to do the fit.<br>
<br>
In your case the fit does not seem perfect, but still reasonable<br>
since the variations in the lattice parameter are only at the<br>
third digit (at most tiny changes in the electronic properties).<br>
<br>
FT<br>
<br>
On Thursday 2017-05-04 20:34, fatima DFT wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Date: Thu, 4 May 2017 20:34:34<br>
From: fatima DFT <<a href="mailto:fatimadft5@gmail.com" target="_blank">fatimadft5@gmail.com</a>><br>
Reply-To: A Mailing list for WIEN2k users <<a href="mailto:wien@zeus.theochem.tuwien.ac.at" target="_blank">wien@zeus.theochem.tuwien.ac.<wbr>at</a>><br>
To: A Mailing list for WIEN2k users <<a href="mailto:Wien@zeus.theochem.tuwien.ac.at" target="_blank">Wien@zeus.theochem.tuwien.ac.<wbr>at</a>><br>
Subject: [Wien] optimization for 225 (cubic) space group<br>
<br>
Dear All,I finished an optimisation for 225 space group with -15% to 25% volume change.<span class=""><br>
<br>
If I plot the optimization cure for different vol parameters, I see the shape of ENE vs. Vol curve changes and the optimised lattice parametes also changes (at<br>
third digit).<br>
<br>
If I plot the curve for -15 to 25% then I get the below curve<br>
<a href="https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/1.ps" rel="noreferrer" target="_blank">https://sites.google.com/site/<wbr>dftfatima5/letter/mailing-list<wbr>-queries/1.ps</a><br>
<br>
<br>
and the optimised lattice parameters are<br>
<br>
21.1924 bohr = 11.2145 Ang<br>
<br>
For -10 to 25%, <br>
<a href="https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/2.ps" rel="noreferrer" target="_blank">https://sites.google.com/site/<wbr>dftfatima5/letter/mailing-list<wbr>-queries/2.ps</a><br>
<br>
21.1984 bohr = 11.2177 Ang<br>
<br>
For -5 to 25%<br>
<a href="https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/3.ps" rel="noreferrer" target="_blank">https://sites.google.com/site/<wbr>dftfatima5/letter/mailing-list<wbr>-queries/3.ps</a><br>
<br>
21.1915 bohr = 11.2140 Ang<br>
<br>
0.0 to 25 %<br>
<a href="https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/4.ps" rel="noreferrer" target="_blank">https://sites.google.com/site/<wbr>dftfatima5/letter/mailing-list<wbr>-queries/4.ps</a><br>
<br>
21.1917 bohr = 11.2141 Ang<br>
for 5.0 to 25 %<br>
<a href="https://sites.google.com/site/dftfatima5/letter/mailing-list-queries/5.ps" rel="noreferrer" target="_blank">https://sites.google.com/site/<wbr>dftfatima5/letter/mailing-list<wbr>-queries/5.ps</a><br>
21.2026 bohr = 11.2199 Ang<br>
<br>
<br>
My query is:<br>
<br>
1. Why the optimised lattice parameters are changing if we select different set of data points? The ground state should be same in all cases. Is it?<br>
2. We see from the lattice parameter the change is at third order, can we take any lattice parameters (a0)? How much the third digit changes the electronic<br>
properties?<br>
<br>
<br>
Warm regards<br>
Fatima<br>
<br>
<br>
</span></blockquote>
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<br></blockquote></div><br></div></div></div>