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Question regarding the k-mesh and q-mesh
http://epwforum.uk/viewtopic.php?f=3&t=722
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Author:  inoka [ Wed Oct 24, 2018 6:50 pm ]
Post subject:  Question regarding the k-mesh and q-mesh

Dear developers

I have few questions ( truly a confusion) regarding the electron bandstructure, phonon dispersion curve, k-mesh and the q-mesh details in the epw calculation.

1. We input the path for the bandstructure from wannier functions in epw.in using wdata(i). However we are not specifying the coarse grid along that path. Is it using the same nk1, nk2 and nk3 for that, or does it has a default value. In one of my cases I used nk1=2, nk2=2 and nk3=2, but the band.kpt file (from its gnuplot) show 379 points which is not compatible with my understanding.

And how the K_POINTS in nscf.in used in the calculation? ( I mean why we have to keep nk1xnk2xnk3 equivalent to the # of points given in nscf.in)


2. For phonon dispersion curve also we are not specifying the path and the grid. With that, how do we get a dispersion curve as you have given in the epw documentation http://epw.org.uk/Documentation/FCCLead (fig.2).

Is it taken from another calculation?

3. Is it not necessary to keep the k points given in scf.in be equal to nscf.in ?


Thank you for you help

Inoka

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