Generating the Yambo databases: Difference between revisions

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== UNDER CONSTRUCTION (CH) ==
UNPACK IN SAME PLACE


In this tutorial we will give a step-by-step demonstration how to generate the Yambo databases starting from a PWscf calculation.
== Prerequisites ==
[[File:HBN-bulk-3x3-annotated.png|thumb|Atomic structure of bulk hBN]]
[[File:HBN2.png|thumb|Atomic structure of 2D hBN]]
'''Material properties''':
* HCP lattice, ABAB stacking
* Four atoms per cell, B and N (16 electrons, )
* Lattice constants: ''a'' = 4.716 [a.u.], ''c/a'' = 2.582
* Plane wave cutoff 40 Ry (1500 RL vectors in wavefunctions)
'''You will need''':
* PWSCF input files and pseudopotentials for hBN bulk (Download here)
* <code>pw.x</code> executable, version 5.0 or later
* <code>p2y</code> executable
Unpack the TARFILE:
$ tar -xcvf hBN-bulk.tar
$ cd hBN/PWSCF
$ ls
hbn_bands.in hbn_nscf.in hbn_scf.in hbn_scf_b.in REFERENCES
== DFT calculations ==
First run the SCF calculation in the usual manner, e.g.
pw.x < hBN_scf.in > hBN_scf.out
and then the non-SCF calculation to generate a set of Kohn-Sham eigenvalues and eigenvectors across a denser k-point mesh and for occupied and unoccupied states:
pw.x < hBN_nscf.in > hBN_nscf.out
Note the presence of the following flags in the input file:
wf_collect=.true.
force_symmorphic=.true.
which are needed for the next step. Full explanations of these variables are given on the [http://www.quantum-espresso.org/wp-content/uploads/Doc/INPUT_PW.html quantum-ESPRESSO input variables page]. After these two runs, you should have a <code>hBN.save</code> directory:
$ ls hBN.save
data-file.xml
== Conversion to Yambo format ==
PWscf output is converted to the Yambo format using the <code>p2y</code> (pwscf to yambo), found in the yambo <code>bin</code> directory.
Enter the <code>hbn.save</code> directory and launch <code>p2y</code>:
$ cd hBN.save
$ p2y
[output]
The code reports some information about the system and generates a <code>SAVE</code> directory:
$ ls
SAVE HB,in etc
$ ls SAVE
ns.db1 ns.wf ns.kb_pp_pwscf
ns.wf_fragments_1_1 ...
ns.kb_pp_pwscf_fragment_1 ...
Finally, let's move the SAVE directory into a new clean folder:
mv SAVE ../YAMBO/
== Advanced users ==
<code>p2y<code> accepts several command line options:
$ p2y -H
dfadsfas
----
Next tutorial: [[Introduction to yambo: input, output and command line interface]]

Latest revision as of 14:53, 23 March 2017

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