abinit/tests/tutoparal/README_mbt.txt

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Tutorial on Many-Body calculations in parallel
alpha-quartz SiO2
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First test: Generation of the WFK file
Standard GS + NSCF calculation to produce the WFK file
with a Gamma-centered 4x4x3 mesh (converged calculations
would require a much denser sampling e.g. 6x6x5 should be ok).
This test does not scale very well with the number of processors since we have
only 9 k-points in the IBZ and we don't use the paralkgb option.
Also the number of bands in the WFK file is not enough to converge the GW
calculations (1200 bands for the screening, 800 for sigma would be needed).
How to run the test:
(mpirun ...) abinit < tmbt_1.files > log_1
then rename the WFK file
mv tmbt_1o_DS2_WFK 443_WFK
In the next steps, we will be using this file to start the GW calculations.
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Second step: Screening calculation with the Adler-Wiser formulation and gwpara=2.
First create a symbolic link for the WFK file
ln -s 443_WFK tmbt_2i_WFK
change the files file, then run the code as usual
(mpirun ...) abinit < tmbt_2.files > log_2
The RPA polarizabilty includes 26 empty bands therefore
this test should scale very well up to 26 processors.
Mind that, for optimal speedup, the number of processors should divide 26.
At the end of the calculation we have to rename the output SCR file
mv tmbt_2o_SCR 443_ppm_SCR
The prefix _ppm means that this SCR file can be used for GW calculations
within the plasmon-pole approximation (only two frequencies have been computed).
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Third step: Screening calculation with the Hilbert transform method and gwpara=2
First create a symbolic link for the WFK file
ln -s 443_WFK tmbt_3i_WFK
change the files file specifying the correct index associated to the test,
then run the code as usual
(mpirun ...) abinit < tmbt_3.files > log_3
This test uses the same number of empty states as the previous step
hence it will scale up to 26 processors.
At the end of the calculation we have to rename the output SCR file
mv tmbt_3o_SCR 443_cd_SCR
The prefix _ppm means that this SCR file can be used for GW calculations
withing the contour-defomation technique.
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Fourth step: GW calculation with the plasmon-pole approximation and gwpara=2.
First create two symbolic links for the WFK and the SCR file
ln -s 443_WFK tmbt_4i_WFK
ln -s 443_ppm_SCR tmbt_4i_SCR
then change the files as usual and issue
(mpirun ...) abinit < tmbt_4.files > log_4
The number of bands is 50, hence the correlation part will scale up to 50 nodes.
The same input file can be used for performing CD calculations provided that we link the correct SCR file using
ln -s 443_cd_SCR tmbt_4i_SCR
and we replace the line
gwcalctyp 0 ppmodel
with
gwcalctyp 2
in the input file
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Fifth step: GW calculation with the plasmon-pole approximation and gwpara=2.
First create a symbolic link for the WFK and the SCR file
ln -s 443_WFK tmbt_5i_WFK
ln -s 443_ppm_SCR tmbt_5i_SCR
change the files file than run the code as usual
(mpirun ...) abinit < tmbt_5.files > log_5
This input file should scale up ... processors.