[Pw_forum] Fwd: Calculation of electron-phonon interaction coefficients
Dear All, I have two questions regarding the calculations of electron-phonon interaction coefficients as described in the user guide: http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_ user_guide/node9.html 1. Is the second step, i.e. the step using a coarse k-point grid for SCF calculations necessary? 2. Setting nq1, nq2, and nq3 in an input file leads to a different q-point coordinates from that generated by the kpoints.x program. Shouldn't the resulting coordinates be the same? Thanks! Andy (Ohio State U, Physics Department) ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
[Pw_forum] Calculation of electron-phonon interaction coefficients
Dear All, I have two questions regarding the calculations of electron-phonon interaction coefficients as described in the user guide: http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide/node9.html 1. Is the second step, i.e. the step using a coarse k-point grid for SCF calculations necessary? 2. Setting nq1, nq2, and nq3 in an input file leads to a different q-point coordinates from that generated by the kpoints.x program. Shouldn't the resulting coordinates be the same? Thanks! Andy (Ohio State U, Physics Department) ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
[Pw_forum] igk files
Dear all,
What data are stored in *.igk{n} files? Also, which f90 code controls the
output of the igk files.
Thanks a lot.
Andy.
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[Pw_forum] k grid points in the calculations of electron-phonon interaction coefficients
In the manual of calculating electron-phonon interaction coefficients: http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide/node9.html Item 1 says that: "The latter MUST contain all [image: $ \bf k$] and [image: $ \bf k$] + [image: $ \bf q$] grid points used in the subsequent electron-phonon calculation" I was wondering how we can make sure that the denser k-point grid contains both the k and k+q grid points? Thank you. Andy. -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20131116/98f85737/attachment.html
[Pw_forum] GDIR in Berry phase calculation
Hi All, I want to calculate polarization in the x direction in real space using the berry phase method. I was wondering which "gdir" I should set in the input file? gdir = 1 or gdir = 2? Thanks for your help. Andy -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20131112/8db331b4/attachment.html
[Pw_forum] HSE calculations
Dear Hashemifar, Thanks for your reply. But the Hartree energy term in the Hamiltonian is also non-local. Isn't it? Andy On Sat, Jan 26, 2013 at 1:14 AM, Seyed Javad Hashemifar < hashemifar at cc.iut.ac.ir> wrote: > My understanding is that, in the HSE functional, 25% of the short range > componet of PBE exchange interaction is replaced with Hartree-Fock > exchange, hence in this kind of calculations, you have a non-local orbital > dependent Hamiltonian. As a result of that the computations are > significantly more expensive that the calculations by using local LDA or > semi-local GGA functionals. > > Regards > SJ Hashemifar > == > Seyed Javad Hashemifar > Department of Physics, Isfahan University of Technology > 84156-83111 Isfahan, Iran > Tel: +98 311 391 2375 Fax:+98 311 3912376 > Email: hashemifar at cc.iut.ac.ir > Group Homepage: http://cmsgroup.iut.ac.ir > Personal Homepage: http://hashemifar.iut.ac.ir > ----------- > > > On Sat, Jan 26, 2013 at 5:14 AM, Caloma Trumica wrote: > >> Dear All, >> >> I have a quick question: >> >> why the HSE-type calculations are much more time consuming than standard >> DFT calculations. >> >> Thanks. >> >> Andy >> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20130126/5f37455c/attachment.html
[Pw_forum] HSE calculations
Dear All, I have a quick question: why the HSE-type calculations are much more time consuming than standard DFT calculations. Thanks. Andy -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20130125/8a306723/attachment.html
[Pw_forum] Imaginary phonon frequency
Dear All, I used nq1 = 4, nq2 = 4, nq3 = 1 to do a phonon calculation. The resulting inequivalent number of q points is 6. After a phonon calculation, all frequencies at these 6 points are real and reasonable. However, when I used these data to get a full phonon dispersion in the first BZ. I found that some q points have imaginary frequencies. Can someone tell me the possible reasons? Thank you. Andy -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/2012/3db056b4/attachment.html
[Pw_forum] Questions about the DFPT review paper
Can someone help answer my questions. Thank you so much! On Wed, Oct 24, 2012 at 7:38 PM, Caloma Trumica wrote: > Dear all, > > I do not understand why the two highlighted places in the attached DFPT > review paper are correct. > > I repeat my questions here: > > 1. Why the contributions from valence bands cancel each other? > > 2. Why the left side of Eq.25 has a null eigenvalue? > > Thank you! > > Andy > -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20121025/80c7e2f3/attachment.html
[Pw_forum] Questions about the DFPT review paper
Dear all, I do not understand why the two highlighted places in the attached DFPT review paper are correct. I repeat my questions here: 1. Why the contributions from valence bands cancel each other? 2. Why the left side of Eq.25 has a null eigenvalue? Thank you! Andy -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20121024/86586156/attachment-0001.html -- next part -- A non-text attachment was scrubbed... Name: RMP_questions.pdf Type: application/pdf Size: 56377 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20121024/86586156/attachment-0001.pdf
[Pw_forum] Rotation matrix
Dear all, I have a quick question about the rotation matrix s(3,3,48). Why each element of it must be an integer? Thank you. Andy -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20121016/3d9744c8/attachment-0001.html
[Pw_forum] K points coordinate type
Dear all, I have a quick question: After calling the subroutine to create a set of k points based on the Monkhorst-Pack method, what is the type of the output coordinates? In other words, are they Cartesian or crystal coordinates? Thank you. Andy Lau -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20121007/c061793c/attachment.html
[Pw_forum] A question about symmetry
Dear all, I have a general question about the symmetry in the Quantum espresso program. For quantities such as the Hellmann-Feynman forces and the stress tensor, why do we need to divide they by the total number of symmetry operations. Dose it mean that any quantity reported in an electronic structure code is an average value? Thank you. Andy Lau Hong Kong -- next part -- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20120930/60278468/attachment.html
[Pw_forum] SYMMETRY REFERENCE
Hi Sonu, Thank you so much! On Fri, Sep 21, 2012 at 9:12 PM, Sonu Kumar <1009ukumar at gmail.com> wrote: > Hi Caloma, > > A good for group theory is : > > Space groups for solid state scientists, > by Gerald Burns, Anthony Michael Glazer. > > good luck > > regards, > sonu > > == > Sonu Kumar > Phd Student,Physics Department > Indian Institute of Technology ,Delhi-110016, India > web:-http://www.iitd.ac.in/ > ====== > > > > On Sat, Sep 22, 2012 at 2:11 AM, Caloma Trumica wrote: > >> Dear All, >> >> I found it is difficult to understand some routine like "set_irr", which >> shows how to obtain the irreducible representations involved in phonon >> calculations. >> >> Could you please recommend some textbook or references related with the >> crystal symmetry. >> >> Thank you very much! >> >> Caloma >> >> ___ >> 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/20120922/85f8bc5b/attachment.htm
[Pw_forum] SYMMETRY REFERENCE
Dear All, I found it is difficult to understand some routine like "set_irr", which shows how to obtain the irreducible representations involved in phonon calculations. Could you please recommend some textbook or references related with the crystal symmetry. Thank you very much! Caloma -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120921/ef3960bd/attachment.htm
[Pw_forum] About DFPT
Dear All, When reading the lecture notes about DFPT, I met following similar terms: "star of q", " q star", I was wondering what are they referred to. Do they mean "q*"? Thank you. Andy -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120321/8f2ec076/attachment.htm
[Pw_forum] Which subroutine is related to the atomic displacement in DFPT
Thanks.Axel. I was wondering how to make perturbations for the ground state wavefunctions in the Phonon code. Isn't it either by atomic displacement or electric field? On Thu, Jan 12, 2012 at 9:41 AM, Axel Kohlmeyer wrote: > On Wed, Jan 11, 2012 at 8:56 PM, Caloma Trumica wrote: > > Dear All, > > > > I could not find the name of the subroutine, which applies a pattern of > > atomic displacements in order to get the wavefunction perturbation in > any q > > vector? Could you please help me out? It is supposed to be hidden > somewhere > > in "PH" folder. > > if you compute perturbations, > there are no displacements. > that is the whole point. > > axel. > > > > > > Thanks. > > > > Andy Lau Postgraduate student from HKUST, China > > > > ___ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://www.democritos.it/mailman/listinfo/pw_forum > > > > > > -- > Dr. Axel Kohlmeyer > akohlmey at gmail.com http://goo.gl/1wk0 > > College of Science and Technology > Temple University, Philadelphia PA, USA. > ___ > 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/20120112/08d5e741/attachment.htm
[Pw_forum] Which subroutine is related to the atomic displacement in DFPT
Dear All, I could not find the name of the subroutine, which applies a pattern of atomic displacements in order to get the wavefunction perturbation in any q vector? Could you please help me out? It is supposed to be hidden somewhere in "PH" folder. Thanks. Andy Lau Postgraduate student from HKUST, China -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120111/f5f86b8c/attachment.htm
[Pw_forum] What is the difference between Q points mesh and k points mesh
Dear All, I have a quick question: When doing phonon calculation for a unit cell, we need to set up a qpoints mesh. This mesh is built also based on M-K scheme, so the resulting coordinates and weight should be exactly the same as those for k points if the input grid is the same? say 5*5*5 for a cubic cell. Is my understanding correct? If so, why do we need to have such an additional setting of q points rather than just using k points mesh for both? Thanks. Caloma Ditrica PhD student from Penn State University -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120108/0c0ae6a8/attachment.htm
[Pw_forum] About cut-off energy
Dear All, I would like to know whether there is some default plane-wave cut-off energy starting to test for each element. Thanks. -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090806/bcb00117/attachment.htm
[Pw_forum] Wavefunction file
Dear All, I do not want to save down the wavefunction file after running PWSCF. How can I set the input file to realize this, thanks. Caloma Trumica University of Washington -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090729/ae0f4a10/attachment.htm
