No, you cannot do that.
You can run x optic on any k-mesh you like and get the momentum
matrix elements.
But you cannot run x joint with an arbitrary k-mesh (I'm even
surprised that it did not crash). joint performs an integration over the
BZ using a tetrahedron method. So it need a tetrahedral mesh (from x kgen).
(You cannot calculate a DOS using x tetra either with an arbitrary
k-mesh (except when using a simple sample method and Gauss broadening).
On 03/24/2017 09:59 AM, Yong Woo Kim wrote:
Dear Wien2k users,
Hello, I am currently working on obtaining transition dipole moment
values of wurtzite ZnO along a path using optic.
I have obtained some results but to check whether they are reasonable, I
have been trying to obtain the refractive index values using x kram.
It seems that if I perform x kram after obtaining the momentum matrix
elements along a certain path, (specified by xcrysden.klist for
bandstructure calculations) I get incorrect refractive index values.
That is I performed something like the following commands.
x lapw1 -band
x optic
x joint
x kram
and opticplot_lapw to see the refractive index curve. Am I not supposed
to do this and perform x optic on a regular k mesh?
I also tried the same thing without the bandstructure calculation part, i.e.
x kgen
x lapw1
x lapw2 -fermi
x optic
x joint
x kram
and the results seemed to be more reasonable but still the refractive
index values were about 0.2 lower than the known values. Is this within
errors of DFT calculation? Or is it too large and I may have done
something wrong?
Also in the end I need to obtain the momentum matrix elements using the
first way, and when I do it should I use a finer k mesh before the band
calculation? That is,
x kgen
x lapw1 -band
x optic
Right now I am just using a value of 1000 used in init_lapw. Could there
be a reasonable value (or minimum value) of k points that should be used?
Thank you very much for reading the long post, and any help will be
greatly appreciated.
Yours Sincerely,
Yong Woo Kim
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Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
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