mirror of https://gitlab.com/QEF/q-e.git
39 lines
1.6 KiB
Plaintext
39 lines
1.6 KiB
Plaintext
EXAMPLE: 2dimensional BN
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This example shows how to use pw2gw.x post processing code to produce the following outputs
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-The optical matrix elements in the dipole approximation , Fermi golden Rule
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(file matrixelements)
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-The imaginary part of the dielectric function for light polarized along the x,y,z directions
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(files epsX.dat, epsY.dat, epsZ.dat) and an average of the three (file epsTOT.dat)
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-The file used as an interface for the dpforexc manybody code (QPLDA)
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(this file is quite big. Set the qplda input parameter to .true. in the pw2gw
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input only if this is needed)
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Note: The convergency of the dielectric function with the kinetic cutoff is much faster,
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hence this example will use a reduced cutoff parameter
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Optical properties converge slowly with k-points mesh. Convergence tests with
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the number of kpoints and with the number of empty states have to be carefully
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performed.
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1) run a self-consistent calculation (input=bn.scf.in,output=bn.scf.out)
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2) run a non self-consistent calculation including several empty bands and more k-points
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(input=bn.nscf.in,output=bn.nscf.out)
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3) run pw2gw.x (input=bn.pw2gw.in,output=bn.pw2gw.out) that reads the wavefunction from the *.save folder
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and uses them to calculate the aforementioned results
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4) Repeat step 2 and 3 increasing the density of the k-mesh and the empty bands in order to study the
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convergence of the optical properties
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