[Pw_forum] bulk projected band structure
Dear all, I'm going to plot bulk projected band structure on a 2D BZ. I'm guessing(take x-y plane 2D for example) for every k point in xy plane (K_x, k_y, 0.0) I have to calculate all other energies with different k_z. By this way the final energy band structure with K index only on xy plane is so-called bulk projected band structure. But one problem for this I need to specify too much k-points, so I am wondering if there is a more efficient way to do this? Can someone share your experience in this? Thanks so much in advance. Jack Ming -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/e71c4db2/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Professor Stefano: You mean when q->0, the polar phonon is described by Huang-equation? If so, I know the answer:) Thank you very much;) On Fri, Apr 29, 2011 at 7:16 PM, Stefano de Gironcoli wrote: > if you really want to know what happens close to gamma... look for the > theory of polaritons. > also of interest can be to look for derivation of Lyddane-Sachs-Teller > relationship. > stefano > > > > On 04/29/2011 12:23 PM, xirainbow wrote: > > Dear Professor Eyvaz: > Thank you very much for your instruction:) > > > When q is zero, there is no longitude and transverse mode. > Really? How about optical modes? Did you pay attention to "O"? > > > I do not express myself clearly. > When q=0, q has no direction. Therefore, optical modes can not be > classified into longitude or transverse ones. As a result, at q=0, these > optical phonon should be still degenerate( LO=TO ). > > > > > Bests, > Eyvaz. > > --- > Prof. Eyvaz Isaev, > Department of Physics, Chemistry, and Biology (IFM), Linkoping University, > Sweden > Theoretical Physics Department, Moscow State Institute of Steel & Alloys, > Russia,isaev at ifm.liu.se, eyvaz_isaev at yahoo.com > > > -- > *From:* xirainbow > *To:* PWSCF Forum > *Sent:* Fri, April 29, 2011 9:30:31 AM > > *Subject:* Re: [Pw_forum] LO-TO splitting in dynmat.x > > Dear Sonu Kumar > What you said is reasonable;) > > I have two little questions. > One: > Does LO-TO splitting must disappear at the boundary of Brillouin zone? > > Two: > I can understand the LO-TO splitting near Gamma point. > However, at Gamma point(not near Gamma point), q=0. When q is zero, there > is no longitude and transverse mode. Why are there LO-TO splitting at Gamma > point? > > Thanks:) > > > > On Fri, Apr 29, 2011 at 1:21 PM, sonu kumar <1009ukumar at gmail.com> > <1009ukumar at gmail.com> wrote: > > > Dear All QE users, > > i am sorry again, as i havn't corrected the subject title. > > > (2) only cubic crystals has LO and TO braches. > > crystals ( having considerable values of macroscopic dielectric constant [ > i suppose > epsilon infinity] and born effective charges, as pointed out by Prof. > Eyvaz Isaev) with low symmetry can, also, have LO-TO splitting. But this can > be different in different symmetry directions, so one has to search all > symmetry directions for this splitting. > > For cubic crystals splitting is equal in all directions. > > with regards, > > -- > Sonu Kumar > > Phd Student > Physics Department > Indian Institute of Technology > Delhi-110016, India > web:-http://www.iitd.ac.in/ > > ___ > Pw_forum mailing listPw_forum at > pwscf.orghttp://www.democritos.it/mailman/listinfo/pw_forum > > -- > > Hui Wang > School of physics, Fudan University, Shanghai, China > > ___ > Pw_forum mailing listPw_forum at > pwscf.orghttp://www.democritos.it/mailman/listinfo/pw_forum > > > ___ > Pw_forum mailing listPw_forum at > pwscf.orghttp://www.democritos.it/mailman/listinfo/pw_forum > > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Hui Wang School of physics, Fudan University, Shanghai, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/16189fb3/attachment-0001.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Huang: Thanks very much for your valuable discussion. I are reading your mentioned paper:) On Fri, Apr 29, 2011 at 5:20 PM, lfhuang wrote: > Dear Wang, H: > > Suppose a uniaxial crystal(no cubic): c>a=b. Suppose there is a > > double-degenerate polar E_u mode, in which all atoms move in the a-b > plane. > > If the wavevector around Gamma point is in the a-b plane, the degenerate > E > > mode will split into LO and TO mode. > > Am I right? > > It is probable for some ionic crystals, but still depends. > Maybe the Equ. 98 (nonanalytic part of the dynamical matrix) in Rev. Mod. > Phys. 73, 515 (2001) by prof. S. Baroni etc. and the related parts in the > book "Dynamical Theory of Crystal Lattices" by M. Born & K. Huang can give > you much information if these things are important/interesting to you. > > In addition, is the method "finite difference" you mentioned exactly the > "frozen phonon" or "small displacement" method? If so, the treatment like > that in PWSCF should be good to obtain a satisfied LO/TO splitting, although > honestly I haven't done this in the "frozen phonon" method. Some people > propose other methods, like using a prolonged supercell, which I think, > could not fully describe the long-range dipolar interaction, because of its > long-range character (as prof. Stefano de Gironcoli said ~1/R^3). > > Best Wishes! > Yours Sincerely > L. F. Huang > -- > == > L.F.Huang(???) DFT and phonon physics > == > Add: Research Laboratory for Computational Materials Sciences, > Instutue of Solid State Physics,the Chinese Academy of Sciences, > P.O.Box 1129, Hefei 230031, P.R.China > Tel: 86-551-5591464-326(office) > Fax: 86-551-5591434 > Our group: http://theory.issp.ac.cn > == > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Hui Wang School of physics, Fudan University, Shanghai, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/bd58dee3/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Professor Eyvaz: Thank you very much for your instruction:) >When q is zero, there is no longitude and transverse mode. > Really? How about optical modes? Did you pay attention to "O"? > I do not express myself clearly. When q=0, q has no direction. Therefore, optical modes can not be classified into longitude or transverse ones. As a result, at q=0, these optical phonon should be still degenerate( LO=TO ). > Bests, > Eyvaz. > > --- > Prof. Eyvaz Isaev, > Department of Physics, Chemistry, and Biology (IFM), Linkoping University, > Sweden > Theoretical Physics Department, Moscow State Institute of Steel & Alloys, > Russia, > isaev at ifm.liu.se, eyvaz_isaev at yahoo.com > > > -- > *From:* xirainbow > *To:* PWSCF Forum > *Sent:* Fri, April 29, 2011 9:30:31 AM > > *Subject:* Re: [Pw_forum] LO-TO splitting in dynmat.x > > Dear Sonu Kumar > What you said is reasonable;) > > I have two little questions. > One: > Does LO-TO splitting must disappear at the boundary of Brillouin zone? > > Two: > I can understand the LO-TO splitting near Gamma point. > However, at Gamma point(not near Gamma point), q=0. When q is zero, there > is no longitude and transverse mode. Why are there LO-TO splitting at Gamma > point? > > Thanks:) > > > > On Fri, Apr 29, 2011 at 1:21 PM, sonu kumar <1009ukumar at gmail.com> wrote: > >> Dear All QE users, >> >> i am sorry again, as i havn't corrected the subject title. >> >> >> (2) only cubic crystals has LO and TO braches. >>> >> >> crystals ( having considerable values of macroscopic dielectric constant [ >> i suppose >> epsilon infinity] and born effective charges, as pointed out by Prof. >> Eyvaz Isaev) with low symmetry can, also, have LO-TO splitting. But this can >> be different in different symmetry directions, so one has to search all >> symmetry directions for this splitting. >> >> For cubic crystals splitting is equal in all directions. >> >> with regards, >> >> -- >> Sonu Kumar >> >> Phd Student >> Physics Department >> Indian Institute of Technology >> Delhi-110016, India >> web:-http://www.iitd.ac.in/ >> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > -- > > Hui Wang > School of physics, Fudan University, Shanghai, China > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Hui Wang School of physics, Fudan University, Shanghai, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/02c19771/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Professor Stefano: Thanks very much for your patient instruction. I will read your mentioned paper carefully. And now, I imagine that the phonon dispersion near Gamma point may look like: ^ Frequency | | *@* |*@****LO* | | * **$**@$ TO* | <---|-> Gamma wavevector near Gamma When q->0, there is LO-TO splitting. When q=0, q has no direction. Therefore, optical modes can not be classified into longitude or transverse ones. As a result, at q=0, *$*=*@.* However, there is not infinite crystal; and electric-static interaction always occurs for finite crystal. Therefore, in experiment, LO-TO splitting exists at the q=0. On Fri, Apr 29, 2011 at 3:16 PM, Stefano de Gironcoli wrote: > the electristatic interaction at the origin of LO-TO splitting is always > present... > > for any q<>0 (even very small) it is included in the calculation. > > in the limit of q->0 in non-metallic systems it gives origin to a non > analytic behavior that must be calculate separately. > > If you want to Fourier interpolate the phonon dispersions calculated on a > regular grid of q-points > you are in trouble because non analyticity of the phonon dispersion implyes > long-range (1/R^3) interatomic force constants and so you need to > > 1) evaluate Z* and epsilon_infty in the limit of q->0 that determine the > non-analyticity > 2) remove from dynamical matrix in every q point in you grid an > electrostatic model that gives the correct non-analyticity for q->0 and is > smooth elsewhere > 3) Fourier interpolate the modified (hopefully short-range) dynamical > matrices > 4) add back the model in any q-point you want to study. > > This is what the sequence ph.x -> q2r.x -> matdyn.x does (in example06 for > instance) > > thete is some discussion of these issues in Review of Modern Physics 73, > 515 (2001) and in Phys Rev 43, 7231 (1991) > > stefano > > On 04/29/2011 05:05 AM, xirainbow wrote: > > Dear Eyvaz: > Thank you very much;) > > > Is there LO-TO splitting far away from Gamma point? > No. > > > Does LO-TO splitting must disappear at the boundary of Brillouin zone? > > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.orghttp://www.democritos.it/mailman/listinfo/pw_forum > > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Hui Wang School of physics, Fudan University, Shanghai, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/afdf814f/attachment-0001.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Wang, H: > Suppose a uniaxial crystal(no cubic): c>a=b. Suppose there is a > double-degenerate polar E_u mode, in which all atoms move in the a-b plane. > If the wavevector around Gamma point is in the a-b plane, the degenerate E > mode will split into LO and TO mode. > Am I right? It is probable for some ionic crystals, but still depends. Maybe the Equ. 98 (nonanalytic part of the dynamical matrix) in Rev. Mod. Phys. 73, 515 (2001) by prof. S. Baroni etc. and the related parts in the book "Dynamical Theory of Crystal Lattices" by M. Born & K. Huang can give you much information if these things are important/interesting to you. In addition, is the method "finite difference" you mentioned exactly the "frozen phonon" or "small displacement" method? If so, the treatment like that in PWSCF should be good to obtain a satisfied LO/TO splitting, although honestly I haven't done this in the "frozen phonon" method. Some people propose other methods, like using a prolonged supercell, which I think, could not fully describe the long-range dipolar interaction, because of its long-range character (as prof. Stefano de Gironcoli said ~1/R^3). Best Wishes! Yours Sincerely L. F. Huang -- == L.F.Huang(???) DFT and phonon physics == Add: Research Laboratory for Computational Materials Sciences, Instutue of Solid State Physics,the Chinese Academy of Sciences, P.O.Box 1129, Hefei 230031, P.R.China Tel: 86-551-5591464-326(office) Fax: 86-551-5591434 Our group: http://theory.issp.ac.cn == -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/a8de247b/attachment.htm
[Pw_forum] Oscillations in macroscopic average of VH+Vbare
Dear all, I am trying to calculate the work function for Cu(100) surface with and without bulk reference. The equations used are as follows: work function w/o bulkref --> wf1 = Vvac - EF,slab work function with bulkref --> wf2 = Vvac - Vslab,int + Vbulk,macro - EF,bulk The problem is that the macroscopic average of VH+Vbare for the slab is oscillating as a function of z (see 05.png). I do not understand why the macroscopic average is oscillating. We want to see the convergence of the work function with the number of atomic layers in the slab. Due to the oscillation in macroscopic average, the work function dramatically changes when we go from 5 to 6 layers (4.86641 eV to 3.62728 eV, respectively). This makes it hard to see the convergence of wf with number of layers. Would it be correct to use the average of the macroscopic average of the peaks and troughs in calculating wf2? Even if we calculate the average of upper oscillations (05.png), I don't know what to do with the trough that comes up just before the vacuum region? Thank you for any help. -- Izaak Williamson Research Assistant Physics Department Boise State University -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/1496c877/attachment-0001.htm -- next part -- A non-text attachment was scrubbed... Name: 05.png Type: image/png Size: 22521 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20110429/1496c877/attachment-0002.png -- next part -- A non-text attachment was scrubbed... Name: Al100.wf.png Type: image/png Size: 17376 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20110429/1496c877/attachment-0003.png
[Pw_forum] LO-TO splitting in dynmat.x
Dear Sonu Kumar What you said is reasonable;) I have two little questions. One: Does LO-TO splitting must disappear at the boundary of Brillouin zone? Two: I can understand the LO-TO splitting near Gamma point. However, at Gamma point(not near Gamma point), q=0. When q is zero, there is no longitude and transverse mode. Why are there LO-TO splitting at Gamma point? Thanks:) On Fri, Apr 29, 2011 at 1:21 PM, sonu kumar <1009ukumar at gmail.com> wrote: > Dear All QE users, > > i am sorry again, as i havn't corrected the subject title. > > > (2) only cubic crystals has LO and TO braches. >> > > crystals ( having considerable values of macroscopic dielectric constant [ > i suppose > epsilon infinity] and born effective charges, as pointed out by Prof. > Eyvaz Isaev) with low symmetry can, also, have LO-TO splitting. But this can > be different in different symmetry directions, so one has to search all > symmetry directions for this splitting. > > For cubic crystals splitting is equal in all directions. > > with regards, > > -- > Sonu Kumar > > Phd Student > Physics Department > Indian Institute of Technology > Delhi-110016, India > web:-http://www.iitd.ac.in/ > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Hui Wang School of physics, Fudan University, Shanghai, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/37e70259/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
if you really want to know what happens close to gamma... look for the theory of polaritons. also of interest can be to look for derivation of Lyddane-Sachs-Teller relationship. stefano On 04/29/2011 12:23 PM, xirainbow wrote: > Dear Professor Eyvaz: > Thank you very much for your instruction:) > >> When q is zero, there is no longitude and transverse mode. >> Really? How about optical modes? Did you pay attention to "O"? >> > I do not express myself clearly. > When q=0, q has no direction. Therefore, optical modes can not be > classified into longitude or transverse ones. As a result, at q=0, these > optical phonon should be still degenerate( LO=TO ). > > > >> Bests, >> Eyvaz. >> >> --- >> Prof. Eyvaz Isaev, >> Department of Physics, Chemistry, and Biology (IFM), Linkoping University, >> Sweden >> Theoretical Physics Department, Moscow State Institute of Steel& Alloys, >> Russia, >> isaev at ifm.liu.se, eyvaz_isaev at yahoo.com >> >> >> -- >> *From:* xirainbow >> *To:* PWSCF Forum >> *Sent:* Fri, April 29, 2011 9:30:31 AM >> >> *Subject:* Re: [Pw_forum] LO-TO splitting in dynmat.x >> >> Dear Sonu Kumar >> What you said is reasonable;) >> >> I have two little questions. >> One: >> Does LO-TO splitting must disappear at the boundary of Brillouin zone? >> >> Two: >> I can understand the LO-TO splitting near Gamma point. >> However, at Gamma point(not near Gamma point), q=0. When q is zero, there >> is no longitude and transverse mode. Why are there LO-TO splitting at Gamma >> point? >> >> Thanks:) >> >> >> >> On Fri, Apr 29, 2011 at 1:21 PM, sonu kumar<1009ukumar at gmail.com> wrote: >> >>> Dear All QE users, >>> >>> i am sorry again, as i havn't corrected the subject title. >>> >>> >>> (2) only cubic crystals has LO and TO braches. >>> crystals ( having considerable values of macroscopic dielectric constant [ >>> i suppose >>> epsilon infinity] and born effective charges, as pointed out by Prof. >>> Eyvaz Isaev) with low symmetry can, also, have LO-TO splitting. But this can >>> be different in different symmetry directions, so one has to search all >>> symmetry directions for this splitting. >>> >>> For cubic crystals splitting is equal in all directions. >>> >>> with regards, >>> >>> -- >>> Sonu Kumar >>> >>> Phd Student >>> Physics Department >>> Indian Institute of Technology >>> Delhi-110016, India >>> web:-http://www.iitd.ac.in/ >>> >>> ___ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >>> >> >> -- >> >> Hui Wang >> School of physics, Fudan University, Shanghai, China >> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/bc08b9ab/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Huang: This could depend on the definition of "LO-TO splitting", which I meant "the > reduction of the LO-TO degeneracy". > I still have another question ?? Suppose a uniaxial crystal(no cubic): c>a=b. Suppose there is a double-degenerate polar E_u mode, in which all atoms move in the a-b plane. If the wavevector around Gamma point is in the a-b plane, the degenerate E mode will split into LO and TO mode. Am I right? -- Hui Wang School of physics, Fudan University, Shanghai, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/4eb8746d/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Huang: I think you are right;) Thanks a lot :P On Fri, Apr 29, 2011 at 11:50 AM, lfhuang wrote: > Dear Wang: > > > LO-TO splitting always exists in Brillouin zone, but two points are worth > > > > noting: > > > > > I do not think so. I do not find any LO-TO splitting at the X and R point > of > > Brillouin zone of cubic. > > This could depend on the definition of "LO-TO splitting", which I meant > "the reduction of the LO-TO degeneracy". > If it is defined to be the splitting due to the long-range electric force > on LO, it will disappear in BZ zone. > > Best Wishes! > Yours Sincerely > L. F. Huang > -- > == > L.F.Huang(???) DFT and phonon physics > == > Add: Research Laboratory for Computational Materials Sciences, > Instutue of Solid State Physics,the Chinese Academy of Sciences, > P.O.Box 1129, Hefei 230031, P.R.China > Tel: 86-551-5591464-326(office) > Fax: 86-551-5591434 > Our group: http://theory.issp.ac.cn > == > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Hui Wang School of physics, Fudan University, Shanghai, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/06c4a3f1/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Wang: > LO-TO splitting always exists in Brillouin zone, but two points are worth > > noting: > > > I do not think so. I do not find any LO-TO splitting at the X and R point of > Brillouin zone of cubic. This could depend on the definition of "LO-TO splitting", which I meant "the reduction of the LO-TO degeneracy". If it is defined to be the splitting due to the long-range electric force on LO, it will disappear in BZ zone. Best Wishes! Yours Sincerely L. F. Huang -- == L.F.Huang(???) DFT and phonon physics == Add: Research Laboratory for Computational Materials Sciences, Instutue of Solid State Physics,the Chinese Academy of Sciences, P.O.Box 1129, Hefei 230031, P.R.China Tel: 86-551-5591464-326(office) Fax: 86-551-5591434 Our group: http://theory.issp.ac.cn == -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/6b85809b/attachment.htm
[Pw_forum] phonon dispersion
Dear Nicola Thanks , I have find the answer . I need ph.x & q2r.x & matdyn,x to get what I want . tanyci ---Original Message--- From: Nicola Marzari Date: 2011-4-27 9:29:31 To: PWSCF Forum Subject: Re: [Pw_forum] phonon dispersion On 4/27/11 2:21 AM, ??? wrote: > Dear all > I want to calculate the phonon dispersion of B12 at the first Brillouin > Zone . i don't know which program should I use ? Please give me some > advice . And if it's possible ,please give me a example ? > > thanks in advance . > Tanyci > Nankai university , tianjin > china Der Tanyci, all the answers to your questions are on the website, including e.g. extensive video lectures and tutorials: www.quantum-espresso.org nicola -- -- Prof Nicola MarzariDepartment of MaterialsUniversity of Oxford Chair of Materials Modelling Director, Materials Modelling Laboratory nicola.marzari at materials.ox.ac.uk http://mml.materials.ox.ac.uk/NM ___ Pw_forum mailing list Pw_forum at pwscf.org http://www.democritos.it/mailman/listinfo/pw_forum -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/7ed9e9a4/attachment-0001.htm -- next part -- A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 11828 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20110429/7ed9e9a4/attachment-0001.jpeg -- next part -- A non-text attachment was scrubbed... Name: not available Type: image/gif Size: 46417 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20110429/7ed9e9a4/attachment-0001.gif
[Pw_forum] LO-TO splitting in dynmat.x
Dear Eyvaz: Thank you very much;) > Is there LO-TO splitting far away from Gamma point? > No. > Does LO-TO splitting must disappear at the boundary of Brillouin zone? -- Hui Wang School of physics, Fudan University, Shanghai, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/43475390/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Huang: Thanks very much for your help:) LO-TO splitting always exists in Brillouin zone, but two points are worth > noting: > I do not think so. I do not find any LO-TO splitting at the X and R point of Brillouin zone of cubic. Because I use finite difference method, I do not know LO-TO splitting persists at other part. > (2) only cubic crystals has LO and TO braches. > The LO-TO splitting exists also in uniaxial crystal(direction dispersion in Raman). -- Hui Wang School of physics, Fudan University, Shanghai, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/245b4fc0/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Just to add a reference, an analysis of the polaritons in non cubic crystals can be found in this article. R. Loudon, Advances in Physics, 2001, Vol. 50, No. 7, 813-864 This article was originall y published in Advances in Physics, volume 13, 1964 . It attracted 1147 citations by October 2001, and is ranked 2 in the index of articles attracting more than 100 citations. -- Eduardo Menendez Departamento de Fisica Facultad de Ciencias Universidad de Chile Phone: (56)(2)9787439 URL: http://fisica.ciencias.uchile.cl/~emenendez -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/7f1cc878/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear All QE users, i am sorry again, as i havn't corrected the subject title. (2) only cubic crystals has LO and TO braches. > crystals ( having considerable values of macroscopic dielectric constant [ i suppose epsilon infinity] and born effective charges, as pointed out by Prof. Eyvaz Isaev) with low symmetry can, also, have LO-TO splitting. But this can be different in different symmetry directions, so one has to search all symmetry directions for this splitting. For cubic crystals splitting is equal in all directions. with regards, -- Sonu Kumar Phd Student Physics Department Indian Institute of Technology Delhi-110016, India web:-http://www.iitd.ac.in/ -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/2528e0c0/attachment.htm
[Pw_forum] Pw_forum Digest, Vol 46, Issue 89
Dear All QE users, > (2) only cubic crystals has LO and TO braches. > crystals ( having considerable values of macroscopic dielectric constant [ i suppose epsilon infinity] and born effective charges, as pointed out by Prof. Eyvaz Isaev) with low symmetry can, also, have LO-TO splitting. But this can be different in different symmetry directions, so one has to search all symmetry directions for this splitting. For cubic crystals splitting is equal in all directions. with regards, -- Sonu Kumar Phd Student Physics Department Indian Institute of Technology Delhi-110016, India web:-http://www.iitd.ac.in/ -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/56697c3e/attachment.htm
[Pw_forum] vdW functional not implemented for spin polarized runs
On Fri, Apr 29, 2011 at 3:49 AM, Stefano de Gironcoli wrote: > Dear all, > > ? ? I inquired Timo Thonhauser (now Wake Forest ?University), the main > character behind the vdW-DF functional implementation in Quantum > ESPRESSO, ?about the issue of the spin-polarized version of vdW-DF. > > I'm reporting his opinion below: > > "In general, at the moment there exists NO true extension of vdW-DF for > spin-polarized cases. Several groups have expressed interest in working > on it, but nothing has been published yet. Note that just evaluating > vdW-DF for the two spin densities separately, while simple to implement, > is an approximation which is difficult to justify: there is no > quantitative measure of the error being made, other than hand waving > arguments that it has to be small. Also, we did not implement that > simple fix, because we were afraid that people would use it as a > black-box for spin-polarized calculations, not knowing that there is no > spin-polarized vdW-DF" > > hope this helps to clarify the situation. > > stefano Thank you Stefano and Thonhauser Timo for the clarification. -- Duy Le PhD Student Department of Physics University of Central Florida. "Men don't need hand to do things" > > > > On 04/27/2011 04:45 PM, Duy Le wrote: >> -- >> Duy Le >> PhD Student >> Department of Physics >> University of Central Florida. >> >> "Men don't need hand to do things" >> >> >> >> On Wed, Apr 27, 2011 at 3:29 AM, Stefano de Gironcoli >> ?wrote: >>> the vdW energy depends on the local polarizability of the electron gas .. >>> does it depend on the spin density ? I would say so. >> I would depend as we expected, however, from the formalism of vdW-DF, >> spin is not taken into account. So, I think in the limit of vdW-DF, >> the spin-dependence is ignored. >> >>> Is it taken into account in the current definition of vdw-DF ? I would say >>> no... >>> how is it implemented in GPAW ? just blindly or with some argument ? >> I am not sure. Did not have a chance to look at it and there is no >> found document about this. >> >>> stefano >>> >>> On 04/27/2011 06:35 AM, WANG Wei wrote: >>> >>> Thank you for your advice, Deu. Yes, the non-local energy is independent the >>> spin density. >>> >>> >>> On 27 April 2011 12:34, Duy Le ?wrote: >>> >>> -- >>> Duy Le >>> PhD Student >>> Department of Physics >>> University of Central Florida. >>> >>> "Men don't need hand to do things" >>> >>> >>> >>> On Tue, Apr 26, 2011 at 1:00 PM, Stefano de Gironcoli >>> wrote: >>> >>> Dear ?WANG Wei >>> ? ?the vdw-DF functional form is not defined for spin polarized system... >>> >>> Or it does mean that non-local energy is not spin-dependent but >>> charge-density-dependent only. >>> >>> ? ?if you define, implement and test it, you could even get a nice >>> publication out of it. thank you. >>> >>> The spin-polarized vdW-DF has been implemented in GPAW. >>> >>> stefano >>> >>> >>> >>> ___ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >>> >>> ___ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >>> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
[Pw_forum] vdW functional not implemented for spin polarized runs
Dear all, I inquired Timo Thonhauser (now Wake Forest University), the main character behind the vdW-DF functional implementation in Quantum ESPRESSO, about the issue of the spin-polarized version of vdW-DF. I'm reporting his opinion below: "In general, at the moment there exists NO true extension of vdW-DF for spin-polarized cases. Several groups have expressed interest in working on it, but nothing has been published yet. Note that just evaluating vdW-DF for the two spin densities separately, while simple to implement, is an approximation which is difficult to justify: there is no quantitative measure of the error being made, other than hand waving arguments that it has to be small. Also, we did not implement that simple fix, because we were afraid that people would use it as a black-box for spin-polarized calculations, not knowing that there is no spin-polarized vdW-DF" hope this helps to clarify the situation. stefano On 04/27/2011 04:45 PM, Duy Le wrote: > -- > Duy Le > PhD Student > Department of Physics > University of Central Florida. > > "Men don't need hand to do things" > > > > On Wed, Apr 27, 2011 at 3:29 AM, Stefano de Gironcoli > wrote: >> the vdW energy depends on the local polarizability of the electron gas .. >> does it depend on the spin density ? I would say so. > I would depend as we expected, however, from the formalism of vdW-DF, > spin is not taken into account. So, I think in the limit of vdW-DF, > the spin-dependence is ignored. > >> Is it taken into account in the current definition of vdw-DF ? I would say >> no... >> how is it implemented in GPAW ? just blindly or with some argument ? > I am not sure. Did not have a chance to look at it and there is no > found document about this. > >> stefano >> >> On 04/27/2011 06:35 AM, WANG Wei wrote: >> >> Thank you for your advice, Deu. Yes, the non-local energy is independent the >> spin density. >> >> >> On 27 April 2011 12:34, Duy Le wrote: >> >> -- >> Duy Le >> PhD Student >> Department of Physics >> University of Central Florida. >> >> "Men don't need hand to do things" >> >> >> >> On Tue, Apr 26, 2011 at 1:00 PM, Stefano de Gironcoli >> wrote: >> >> Dear WANG Wei >>the vdw-DF functional form is not defined for spin polarized system... >> >> Or it does mean that non-local energy is not spin-dependent but >> charge-density-dependent only. >> >>if you define, implement and test it, you could even get a nice >> publication out of it. thank you. >> >> The spin-polarized vdW-DF has been implemented in GPAW. >> >> stefano >> >> >> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum
[Pw_forum] dos calculation
On Apr 29, 2011, at 1:42 , wumindt2 wrote: > Since i didn't collect the wavefunctions, the wavefunction files > and the *.save file are in two different directory. > To do the dos calculation, i set the 'outdir' as the directory of > wavefunctions. But then i got an error saying that the *.save > file was not found. if you have problems with the disk quota on the other directory, just move the *.save directory into "outdir" P. -- Paolo Giannozzi, Dept of Chemistry, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
[Pw_forum] LO-TO splitting in dynmat.x
the electristatic interaction at the origin of LO-TO splitting is always present... for any q<>0 (even very small) it is included in the calculation. in the limit of q->0 in non-metallic systems it gives origin to a non analytic behavior that must be calculate separately. If you want to Fourier interpolate the phonon dispersions calculated on a regular grid of q-points you are in trouble because non analyticity of the phonon dispersion implyes long-range (1/R^3) interatomic force constants and so you need to 1) evaluate Z* and epsilon_infty in the limit of q->0 that determine the non-analyticity 2) remove from dynamical matrix in every q point in you grid an electrostatic model that gives the correct non-analyticity for q->0 and is smooth elsewhere 3) Fourier interpolate the modified (hopefully short-range) dynamical matrices 4) add back the model in any q-point you want to study. This is what the sequence ph.x -> q2r.x -> matdyn.x does (in example06 for instance) thete is some discussion of these issues in Review of Modern Physics 73, 515 (2001) and in Phys Rev 43, 7231 (1991) stefano On 04/29/2011 05:05 AM, xirainbow wrote: > Dear Eyvaz: > Thank you very much;) > >> Is there LO-TO splitting far away from Gamma point? >> No. >> > Does LO-TO splitting must disappear at the boundary of Brillouin zone? > > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/093d10e5/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Wang, H.: LO-TO splitting always exists in Brillouin zone, but two points are worth noting: (1) it is caused by short-range interactions, which are calculated directly from DFPT. The splitting at Gamma point is due to long-range dipolar interaction, which needs postprocessing with Born charge; (2) only cubic crystals has LO and TO braches. Best Wishes! Yours Sincerely L. F. Huang > From: xirainbow > Subject: Re: [Pw_forum] LO-TO splitting in dynmat.x > To: PWSCF Forum > Message-ID: > Content-Type: text/plain; charset="iso-8859-1" > > Dear all: > Is there LO-TO splitting far away from Gamma point? > How large is the influence range of LO-TO splitting in Brillouin zone? One > hundred percent? > Thanks in advance;) > > -- > > Hui Wang > School of physics, Fudan University, Shanghai, China -- == L.F.Huang(???) DFT and phonon physics == Add: Research Laboratory for Computational Materials Sciences, Instutue of Solid State Physics,the Chinese Academy of Sciences, P.O.Box 1129, Hefei 230031, P.R.China Tel: 86-551-5591464-326(office) Fax: 86-551-5591434 Our group: http://theory.issp.ac.cn == -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/4de8c29b/attachment-0001.htm
[Pw_forum] Problems about QHA
There is two problems as I known. First, gfortran cannot deal with the non-integer temperature step, so you would receive some warnings. Second, try to ignore the compiling option '-static' in makefile, since both of ifort 2011 and gfortran is not seemed to support '-static' parameter. At 2011-04-29 00:45:23?"zafar rasheed" wrote: Dear Eyvaz Isaev We have just started use Quantum Espresso (since one years ago) . We want to calculat thermal properties (coefficient of thermal expansion, Cp, Cv etc.). But we can not create*.x files of QHA folder. We are using Fedora core 7 (on Simple P4 computer having 2GHz processor , 256 RAM) having gfortran compiler. We change FC in Makefile ( ifort to gfortran) but*.x files does not work. Please help us in this aspect. Best Regards Zafar Rasheed PhD Student Department of Physics The Islamia University of Bahawalpur, Pakistan -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/9c5a/attachment.htm
[Pw_forum] dos calculation
Dear All, I meet a problem with the Dos calculation using projwfc.x. Due to the limit of the disk quota, i need to store the wf files to other directory. So i set the 'outdir' and 'wfcdir' with two different directories. In the discription of projwfc.x, it said that wavefunciton files are needed to calculate the DOS. Since i didn't collect the wavefunctions, the wavefunction files and the *.save file are in two different directory. To do the dos calculation, i set the 'outdir' as the directory of wavefunctions. But then i got an error saying that the *.save file was not found. Does it mean that the 'outdir' and 'wfcdir' should have the same directories? Or otherwise i need to collect the wavefunctions to the *.save file ? Looking forward to your reply. Thanks so much! Min Wu -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/4c161836/attachment.htm
[Pw_forum] LO-TO splitting in dynmat.x
Dear Wang, Let me reiterate: LO-TO splitting takes place ONLY at the Gamma point. Why? It is the physics. Please read at least the review paper I mentioned in my previous mail. Or take a good textbook. >For cubic crystals splitting is equal in all directions. So, for non-cubic LO-TO splitting also occurs and the splitting is different for different directions. That is why one can see a discontinuity near the Gamma point in phonon dispersion relations. >When q is zero, there is no longitude and transverse mode. Really? How about optical modes? Did you pay attention to "O"? Bests, Eyvaz. --- Prof. Eyvaz Isaev, Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com From: xirainbow <nkxirain...@gmail.com> To: PWSCF Forum Sent: Fri, April 29, 2011 9:30:31 AM Subject: Re: [Pw_forum] LO-TO splitting in dynmat.x Dear Sonu Kumar What you said is reasonable;) I have two little questions. One: Does LO-TO splitting must disappear at the boundary of Brillouin zone? Two: I can understand the LO-TO splitting near Gamma point. However, at Gamma point(not near Gamma point), q=0. When q is zero, there is no longitude and transverse mode. Why are there LO-TO splitting at Gamma point? Thanks:) On Fri, Apr 29, 2011 at 1:21 PM, sonu kumar <1009ukumar at gmail.com> wrote: Dear All QE users, > >i am sorry again, as i havn't corrected the subject title. > > > >(2) only cubic crystals has LO and TO braches. >> >crystals ( having considerable values of macroscopic dielectric constant [ i >suppose >epsilon infinity] and born effective charges, as pointed out by Prof. Eyvaz >Isaev) with low symmetry can, also, have LO-TO splitting. But this can be > different in different symmetry directions, so one has to search all symmetry >directions for this splitting. > >For cubic crystals splitting is equal in all directions. > >with regards, > >-- >Sonu Kumar > >Phd Student >Physics Department >Indian Institute of Technology >Delhi-110016, India >web:-http://www.iitd.ac.in/ > >___ >Pw_forum mailing list >Pw_forum at pwscf.org >http://www.democritos.it/mailman/listinfo/pw_forum > > -- Hui Wang School of physics, Fudan University, Shanghai, China ------ next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/81926e79/attachment.htm
