<div dir="ltr"><br><div class="gmail_extra">Dear Prof. Marks,<br><br>Thank you very much for the conceptual reply.<br><br></div><div class="gmail_extra">I am unable to answer the second point now but please see for 1st and 3rd point:<br><br></div><div class="gmail_extra">I agree that some time hybrid calculations may fail for some systems. May you also want to point out that with element from high Z a -SO correction is needed. But in some reputed papers (Nano. letters) it is mention that -SO does not affect much for my system.<br> <br></div><div class="gmail_extra"><br></div><div class="gmail_extra">Regarding, PBESol: in two of PRB papers of Prof. Peter, it is mentioned that PBESol and WC-GGA are better for optimization "PhysRevB.79.155107.pdf", PHYSICAL REVIEW B 79, 085104 2009 . The same trend I am getting where LDA is underestimating the lattice parameter optimization and PBE is overestimating for a list of materials that I have testes.<br><br></div><div class="gmail_extra">WC-GGA and PBESol are giving the optimized lattice parameters in the vicinity of Exp lattice parameters (~0.01-~0.02 Ang reduced). So I used PBESol with mBJ.<br><br></div><div class="gmail_extra">Yes, I also do agree that according to UG, LDA or PBE are good for mBJ but as PBESol gave me well-optimized results so I used PBESol with mBJ.<br><br></div><div class="gmail_extra"><br></div><div class="gmail_extra">So I am not able to find out the solution to my issue; Why the bandgap is drastically reducing if I use "double relaxed structure": <br><br>1. relaxed>> 2. optimization of lattice parameter without relaxing>>> 3. again relaxing the structure (using relaxed structure from step 1 and optimized lattice parameter from step 2.).<br><br></div><div class="gmail_extra">I am sure the procedure used above seems wrong but I am not able to justify the "double relaxation of the structure.<br><br><br></div><div class="gmail_extra">regards,<br><br></div><div class="gmail_extra">Bhamu <br></div><div class="gmail_extra"><br><br> <br></div><div class="gmail_extra"><br><br><br></div><div class="gmail_extra"><br></div><div class="gmail_extra"><div class="gmail_quote">On Thu, Feb 8, 2018 at 6:48 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:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="auto">Inlined, please think:</div><div dir="auto"><br></div><div class="gmail_extra" dir="auto"><div class="gmail_quote">On Feb 8, 2018 7:08 AM, "Dr. K. C. Bhamu" <<a href="mailto:kcbhamu85@gmail.com" target="_blank">kcbhamu85@gmail.com</a>> wrote:<br type="attribution"><blockquote class="gmail-m_-8642702343821586463quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<div dir="ltr">
<div>Dear Prof. Marks,<br>
<br>
</div>
I believe I am having to understand about the mentioned points:<br>
<br>
<div class="gmail_extra">
<div>
<div class="gmail-m_-8642702343821586463m_2740426486863584586gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div dir="auto"><div class="gmail-m_-8642702343821586463quoted-text">
<div dir="ltr"><span style="font-size:12.8px"></span></div>
<br>
<div dir="auto">1) Why is your number for the band gap "wrong", whereas what someone else calculated with HSE is "right"?<br>
<br>
</div>
</div><div dir="auto">Ans: Maybe you want to ask me why the band gap from my calculations should be fine instead of HSE. If so, then I shall mention that hybrid calculations are already a well know approach to predict the band gap of inorganic systems.<br></div></div></div></div></div></div></div></div></div></div></div></div></blockquote></div></div><div dir="auto"><br></div><div dir="auto">Does that mean HSE is right?</div><div class="gmail_extra" dir="auto"><div class="gmail_quote"><blockquote class="gmail-m_-8642702343821586463quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div dir="ltr"><div class="gmail_extra"><div><div class="gmail-m_-8642702343821586463m_2740426486863584586gmail_signature"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="auto"><div dir="auto">
<br>
</div>
<div dir="auto">2) What is the purpose of optimizing internal and cell parameters?<br>
<br>
</div>
<div>Ans: To get the minimum forces on the system and by doing total optimization the system would be in the most stable ground state and can give accurate properties if the most suitable approach is applied!!<br>
<br></div></div></div></div></div></div></div></div></div></div></div></div></blockquote></div></div><div dir="auto">Why? </div><div class="gmail_extra" dir="auto"><div class="gmail_quote"><blockquote class="gmail-m_-8642702343821586463quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div dir="ltr"><div class="gmail_extra"><div><div class="gmail-m_-8642702343821586463m_2740426486863584586gmail_signature"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="auto"><div>
</div><div class="gmail-m_-8642702343821586463quoted-text">
<div dir="auto"><br>
</div>
<div dir="auto">3) Are the cell and internal parameters of PBEsol the same as what they should be with mBJ? What does "should be" mean here?<br>
<br>
</div>
</div><div>Ans: Yes, structure file is same for PBESol and mBJ. According to me you wanted to ask me whether I have applied any changes in mBJ calculation, like relaxation (which is not possible and I did not apply).<br>
</div>
<div class="gmail_extra">I just did PBESol scf >> save_lapw case_scf>>> one scf cycle>> save_lapw mbjx_grr >>> spacified the mBJ approach and finally mBJ scf.<br>
<br>
</div></div></div></div></div></div></div></div></div></div></div></div></blockquote></div></div><div dir="auto">Why should a PBEsol refined structure be optimal for mBJ?</div><div class="gmail_extra" dir="auto"><div class="gmail_quote"><blockquote class="gmail-m_-8642702343821586463quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div dir="ltr"><div class="gmail_extra"><div><div class="gmail-m_-8642702343821586463m_2740426486863584586gmail_signature"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="auto"><div class="gmail_extra">
<br>
</div>
<div class="gmail_extra">regards<br>
</div><div class="gmail-m_-8642702343821586463elided-text">
<div class="gmail_extra">Bhamu<br>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Feb 8, 2018 3:41 AM, "Dr. K. C. Bhamu" <<a href="mailto:kcbhamu85@gmail.com" target="_blank">kcbhamu85@gmail.com</a>> wrote:<br type="attribution">
<blockquote class="gmail-m_-8642702343821586463m_2740426486863584586m_-4756249324881572945quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<div dir="auto">No, I said the calculated gal is ~0.3eV less then the reported gap: HSE.
<div dir="auto"><br>
<div dir="auto"><br>
</div>
<div dir="auto">I tested this on more than 10 systems and in each case obsessed this band gap discrepancy.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Regards</div>
<font color="#888888">
<div dir="auto">Bhamu</div>
</font></div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">
<div class="gmail-m_-8642702343821586463m_2740426486863584586m_-4756249324881572945elided-text">On Feb 8, 2018 3:05 PM, <<a href="mailto:tran@theochem.tuwien.ac.at" target="_blank">tran@theochem.tuwien.ac.at</a>> wrote:<br type="attribution">
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div class="gmail-m_-8642702343821586463m_2740426486863584586m_-4756249324881572945elided-text">A band gap of 0.3 eV is very small and a change of lattice constant may<br>
be enough to close the band gap.<br>
<br>
On Thursday 2018-02-08 10:30, Dr. K. C. Bhamu wrote:<br>
<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 class="gmail-m_-8642702343821586463m_2740426486863584586m_-4756249324881572945elided-text">Date: Thu, 8 Feb 2018 10:30:29<br>
From: Dr. K. C. Bhamu <<a href="mailto:kcbhamu85@gmail.com" target="_blank">kcbhamu85@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: Re: [Wien] a note on lattice parameter optimization<br>
<br>
Yes, I used PBESol followed by mBJ.<br>
<br>
On Feb 8, 2018 2:28 PM, <<a href="mailto:tran@theochem.tuwien.ac.at" target="_blank">tran@theochem.tuwien.ac.at</a>> wrote:<br>
Hi,<br>
<br>
Did you use mBJ to calculate the band gap in both procedures?<br>
<br>
FT<br>
<br>
On Thursday 2018-02-08 09:35, Dr. K. C. Bhamu wrote:<br>
<br>
Date: Thu, 8 Feb 2018 09:35:08<br>
From: Dr. K. C. Bhamu <<a href="mailto:kcbhamu85@gmail.com" target="_blank">kcbhamu85@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] a note on lattice parameter optimization<br>
<br>
Hello,<br>
<br>
Using experimental lattice parameters(a Ang), I optimized the structure with two options.<br>
<br>
1. Directly optimized the structure without min_lapw ... and the optimized lattice parameters are in the vicinity of Exp a (~0.01 Ang accuracy) and the calculated band gap (from mBJ2) is in agreement with reported value ~0.3 eV less.<br>
<br>
2. First relaxed the structure and then optimized this relaxed structure (without min_lapw ....). In this case the optimized lattice parameters are reduced by ~0.05 Ang and the band gap vanished or largely reduced.<br>
<br>
<br>
Why is the second way of doing band structure not working?<br>
<br>
I tested it on many systems. In some case system became metal and in some cases band gap largely reduced when I used the fully relaxed structure for optimization.<br>
<br>
<br>
Thanks,<br>
<br>
<br>
Bhamu<br>
<br>
<br>
<br>
<br>
<br>
<br>
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