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<p>Hi everyone,</p>
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<p>I am trying to calculate thermal conductivity of a graphene nanoribbon throught other program called "phono3py", which uses QE to perform ab initio calculations. Then, in order to understand and validating my results, i am currently trying to calculate the
phonon bands of a different sized graphene nanoribbon, using the so called phonopy.</p>
<p>Firstly, i succesfully solved the infinite (phonon bands) grapehene system with phonopy+QE. Now, I have looked for propper inputs in QE forums for a nanorribon, but i do not know if the input i am using is well posed. Using a single gamma k point (as i read
in this forum), results are ridicolous. Now, using these k-points it lasts for 24 hours for a sigle .in calculation (there are 11 more in a band calculation).</p>
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<div>&control<br>
calculation = 'scf'<br>
prefix='grapheneph',<br>
tprnfor = .true.<br>
tstress = .true.<br>
pseudo_dir = './',<br>
outdir='./saleph51/'<br>
/<br>
&system<br>
ibrav = 0,<br>
nat = 84,<br>
ntyp = 1,<br>
occupations = 'smearing'<br>
smearing = 'm-p'<br>
degauss = 0.01<br>
ecutwfc = 30.0,<br>
ecutrho = 150.0,<br>
/<br>
&electrons<br>
mixing_beta= 0.7<br>
conv_thr = 1.0d-8<br>
diagonalization = 'david'<br>
mixing_mode = 'plain'<br>
/<br>
<b>K_POINTS automatic<br>
12 12 1 0 0 0</b><br>
! ibrav = 0, nat = 84, ntyp = 1<br>
CELL_PARAMETERS bohr<br>
29.8200000000000003 0.0000000000000000 0.0000000000000000<br>
0.0000000000000000 16.1490000000000009 0.0000000000000000<br>
0.0000000000000000 0.0000000000000000 10.0000000000000000<br>
ATOMIC_SPECIES<br>
C 12.01070 C.pbe-rrkjus.UPF</div>
<span>ATOMIC_POSITIONS crystal</span>
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<p>[...]<br>
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<p>I read that is convenient to use a multiple of 3 k-point mesh to achieve better results in any direction (i read for instance 12 or even 60!). Since my system is flat, i set that k-point mesh in x-y.
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<p>So the question is, is this input fine? Do will solve the energy problem (DFT ) accurately?</p>
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<p>Thank you for your time and patience!</p>
<p>Pablo.<br>
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