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<p class="MsoNormal">Hi Prof. Giannozzi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">It worked with the test case mentioned in first email. I believe it should work fine with other test cases of QE, too.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best,<o:p></o:p></p>
<p class="MsoNormal">Phil<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> Paolo Giannozzi <p.giannozzi@gmail.com> <br>
<b>Sent:</b> Monday, August 3, 2020 7:27 AM<br>
<b>To:</b> General discussion list for Quantum ESPRESSO developers <developers@lists.quantum-espresso.org><br>
<b>Cc:</b> Phil Wang <ywang393@jhu.edu><br>
<b>Subject:</b> Re: [QE-developers] Potential Issue with Inversion Symmetry Detection in ph.x<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p><b><br>
</b><strong><span style="font-size:12.0pt;font-family:"Calibri",sans-serif;color:white;background:red"> External Email - Use Caution </span></strong><o:p></o:p></p>
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<p class="MsoNormal">Thank you for noticing this hard-to-notice problem. Does the attached patch fix the problem? Paolo<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Sat, Aug 1, 2020 at 8:54 AM Phil Wang <<a href="mailto:ywang393@jhu.edu">ywang393@jhu.edu</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Dear developers of QE,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hope you are all doing well in this hard time!<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I’m trying to fix conflictions between the k-point branch and the phonon code (Merge Request !292). As I was debugging the search of small group of q points, I found the inversion
detection of ph.x could get wrong result. The part of the code is in LR_Modules/set_small_group_of_q.f90, Line 54 – Line 62:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> nsymq = copy_sym ( nsym, sym )<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
!<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
CALL inverse_s ( )<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
!<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
! check if inversion (I) is a symmetry. If so, there should be nsymq/2<o:p></o:p></p>
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! symmetries without inversion, followed by nsymq/2 with inversion<o:p></o:p></p>
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! Since identity is always s(:,:,1), inversion should be s(:,:,1+nsymq/2)<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
!<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
invsymq = ALL ( s(:,:,nsymq/2+1) == -s(:,:,1) )<o:p></o:p></p>
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<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Since the list of sym ops in s(:,:,48) has been rotated by copy_sym() once for each distinct q point, there is no guarantee that inversion symmetry must sit at “nsymq/2 + 1”. It’s
true only if copy_sym() is called once on s(:,:,48). <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">As an example, I ran phonon on Si with a 4x4x4 q point grid. The small group of (0.5,-0.5,0.5) had inversion, but it’s listed at 9 out of 12 operations. Invsymq was subsequently
set to .False.. The list of sym. ops. for small group of this q, in the order after calling copy_sym(), is:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
identity <o:p></o:p></p>
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inv. 180 deg rotation - cart. axis [-1,0,1] <o:p></o:p></p>
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120 deg rotation - cart. axis [-1,1,-1] <o:p></o:p></p>
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inv. 180 deg rotation - cart. axis [1,1,0] <o:p></o:p></p>
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120 deg rotation - cart. axis [1,-1,1] <o:p></o:p></p>
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inv. 180 deg rotation - cart. axis [0,1,1] <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
180 deg rotation - cart. axis [0,1,1] <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
inversion <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
180 deg rotation - cart. axis [-1,0,1] <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
180 deg rotation - cart. axis [1,1,0] <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
inv. 120 deg rotation - cart. axis [1,-1,1] <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
inv. 120 deg rotation - cart. axis [-1,1,-1] <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">A simple fix would be to replace the line “invsymq = ALL ( s(:,:,nsymq/2+1) == -s(:,:,1) )” by an iteration over the first nsymq operations of s(:,:,48). Although this invsymq is
not propagated to other routines, it might be worth checking similar places of searching inversion in other parts of phonon code / LR code.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">The confliction of git branch “k-point” is almost fixed, and a detailed description can be found at:
<a href="https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Farxiv.org%2Fabs%2F1907.13610&data=02%7C01%7Cywang393%40jhu.edu%7Ce25f70774cd040f4d84508d837a03314%7C9fa4f438b1e6473b803f86f8aedf0dec%7C0%7C0%7C637320508474483929&sdata=5kL%2BAasdvtEI6QcIK4ufWMgasHzM41ktErTSIWArlKw%3D&reserved=0" target="_blank">
https://arxiv.org/abs/1907.13610</a>. Any opinion and suggestion on its integration with QE are welcomed and appreciated!<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Best wishes,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Yunzhe (Phil) Wang<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Mueller Research Group<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Department of Materials Science and Engineering<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Johns Hopkins University<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal">_______________________________________________<br>
developers mailing list<br>
<a href="mailto:developers@lists.quantum-espresso.org" target="_blank">developers@lists.quantum-espresso.org</a><br>
<a href="https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.quantum-espresso.org%2Fmailman%2Flistinfo%2Fdevelopers&data=02%7C01%7Cywang393%40jhu.edu%7Ce25f70774cd040f4d84508d837a03314%7C9fa4f438b1e6473b803f86f8aedf0dec%7C0%7C0%7C637320508474483929&sdata=INce%2BTp5zN%2Fy3Sxv6dcgV2IXqSuJzl2ClKqwqD596WY%3D&reserved=0" target="_blank">https://lists.quantum-espresso.org/mailman/listinfo/developers</a><o:p></o:p></p>
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-- <o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,<br>
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>
Phone +39-0432-558216, fax +39-0432-558222<o:p></o:p></p>
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