<div dir="ltr"><div><div><div><div><div><div>Dear Dr. Paulatto,<br><br></div>Thanks for your reply. However:<br><br></div>a) I still do not understand why this subroutine is necessary.<br>b) "if a point q is on the border of the WS cell, it finds the number N<br>
of translationally equivalent point q+G (where G is a lattice vector)<br>
that are also on the border of the cell. Than, weight = 1/N".<br></div>What I do not understand from the above mentioned statement is, in this wsweight subroutine, the expanded Wigner-Seitz cell is constructed in the REAL space keeping in mind a finite no. of nearest neighbors. The weights are subsequently calculated based on the distance between the atoms. If that is the case, how does the concept of q-point fit here, since q-points belong to the RECIPROCAL space.<br>
</div>c) Is it possible to obtain Fourier interpolation of dynamical matrices without the use of wsweight?<br><br></div>I would really appreciate if you could shed some light on these issues.<br><br></div>Many thanks once again! :-)<br>
<div><br>Cheers,<br><br>Aaditya<br><div><div><div><div><div><div><br><br><div class="gmail_extra"><br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
5. Question on the wsweight subroutine (Aaditya Manjanath)<br>
6. Re: Question on the wsweight subroutine (Lorenzo Paulatto)<br>
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Message: 5<br>
Date: Fri, 29 Mar 2013 21:57:33 +0530<br>
From: Aaditya Manjanath <<a href="mailto:aadipotter@gmail.com">aadipotter@gmail.com</a>><br>
Subject: [Pw_forum] Question on the wsweight subroutine<br>
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Dear all,<br>
<br>
I was looking through the matdyn program wherein the dynamical matrices are<br>
calculated at any q-point through Fourier interpolation and I came across<br>
the wsweight subroutine.<br>
<br>
I know that this subroutine calculates the weight factors that are used in<br>
the Fourier interpolation formula.I tried calculating the dynamical matrix<br>
at a point (0 0.6667 0, say) without using the weight factors and<br>
interestingly, I found that the values of the dynamical matrix obtained<br>
through matdyn do not match with those calculated directly.<br>
<br>
I would like to know, what is the purpose/logic of this subroutine, since I<br>
see that this is an essential part in calculating the dynamical matrices at<br>
arbitrary q-points.<br>
<br>
I would be grateful if you could shed some light on this problem.<br>
<br>
Cheers,<br>
<br>
Aaditya<br>
<br>
--<br>
"Stay hungry. Stay Foolish" - Steve Jobs<br>
<br>
Om Sri Sairam<br>
Best Regards,<br>
Aaditya Manjanath<br>
PhD Engineering Programme<br>
Interdisciplinary Program - Nanoscience and Engineering<br>
Indian Institute of Science<br>
Bangalore - 560012<br>
<br>
Webpage - <a href="http://mrc.iisc.ernet.in/~abhishek/Aaditya.html" target="_blank">http://mrc.iisc.ernet.in/~abhishek/Aaditya.html</a><br>
Email ID - <a href="mailto:aadipotter@gmail.com">aadipotter@gmail.com</a>, <a href="mailto:aaditya.m@cense.iisc.ernet.in">aaditya.m@cense.iisc.ernet.in</a><br>
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Message: 6<br>
Date: Fri, 29 Mar 2013 17:52:45 +0100<br>
From: Lorenzo Paulatto <<a href="mailto:lorenzo.paulatto@impmc.upmc.fr">lorenzo.paulatto@impmc.upmc.fr</a>><br>
Subject: Re: [Pw_forum] Question on the wsweight subroutine<br>
To: PWSCF Forum <<a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a>><br>
Message-ID: <<a href="mailto:5155C6DD.4090807@impmc.upmc.fr">5155C6DD.4090807@impmc.upmc.fr</a>><br>
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On 03/29/2013 05:27 PM, Aaditya Manjanath wrote:<br>
I would like to know, what is the purpose/logic of this subroutine,<br>
since I see that this is an essential part in calculating the dynamical<br>
matrices at arbitrary q-points.<br>
><br>
> I would be grateful if you could shed some light on this problem.<br>
<br>
Dear Aaditya,<br>
wsweights does a very simple task in a very complicated way. It assigns<br>
this weights:<br>
1) if a point is inside the Wigner-Seitz cell: weight=1<br>
2) if a point is outside the WS cell: weight=0<br>
3) if a point q is on the border of the WS cell, it finds the number N<br>
of translationally equivalent point q+G (where G is a lattice vector)<br>
that are also on the border of the cell. Than, weight = 1/N<br>
<br>
I.e. if a point is on the surface of the WS cell of a cubic lattice<br>
it'll have weight 1/2, on the vertex of the WS it would be 1/8; the K<br>
point of an hexagonal lattice has weight 1/3 and so on.<br>
<br>
It takes some thought and some time to understand wsweight; if I<br>
remember correctly, Schwarz inequality is used <<br>
<a href="http://en.wikipedia.org/wiki/Cauchy%E2%80%93Schwarz_inequality" target="_blank">http://en.wikipedia.org/wiki/Cauchy%E2%80%93Schwarz_inequality</a>><br>
<<a href="http://en.wikipedia.org/wiki/Cauchy%E2%80%93Schwarz_inequality" target="_blank">http://en.wikipedia.org/wiki/Cauchy%E2%80%93Schwarz_inequality</a>><br>
<br>
bests<br>
<br>
<br>
--<br>
Dr. Lorenzo Paulatto<br>
IdR @ IMPMC -- CNRS & Universit? Paris 6<br>
phone: +33 (0)1 44275 084 / skype: paulatz<br>
www: <a href="http://www-int.impmc.upmc.fr/~paulatto/" target="_blank">http://www-int.impmc.upmc.fr/~paulatto/</a><br>
mail: 23-24/4?16 Bo?te courrier 115, 4 place Jussieu 75252 Paris C?dex 05<br>
<br>
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</blockquote></div><br><br>-- <br><div dir="ltr"><div>"Stay hungry. Stay Foolish" - Steve Jobs</div><div><br></div><div>Om Sri Sairam</div>Best Regards,<br>Aaditya Manjanath<div>PhD Engineering Programme</div><div>
Interdisciplinary Program - Nanoscience and Engineering</div><div>Indian Institute of Science</div><div>Bangalore - 560012<br><br>Webpage - <a href="http://mrc.iisc.ernet.in/%7Eabhishek/Aaditya.html" target="_blank">http://mrc.iisc.ernet.in/~abhishek/Aaditya.html</a></div>
<div>Email ID - <a href="mailto:aadipotter@gmail.com" target="_blank">aadipotter@gmail.com</a>, <a href="mailto:aaditya.m@cense.iisc.ernet.in" target="_blank">aaditya.m@cense.iisc.ernet.in</a><br>Skype - aadipotter<br></div>
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