Dear Abualnaja ,
how did you chose the smearing and k-point combination ?
your degauss (0.1 Ry =1.36 eV) looks huge to me, while your k-point
grid looks very dense.
mp smearing is a good choice for *real* metals (with a significant
dos(e_F)) even if someone would favor mv smearing. I think that in the
case of graphene with vanishing dos(e_F) the simpler gaussian broadening
should be fine and possibly preferable.
stefano
On 21/04/2016 20:32, Abualnaja, Faris wrote:
Apologies all in the q2r and matdyn files zasr and asr should both be
'simple' and NOT 'crystal'
------------------------------------------------------------------------
*From:* [email protected] <[email protected]> on
behalf of Abualnaja, Faris <[email protected]>
*Sent:* 21 April 2016 16:42
*To:* [email protected]
*Subject:* [Pw_forum] Graphene Phonons Not Working
To whom it may concern,
I've been having trouble lately trying to produce graphene phonon
dispersion plots. I am currently using quantum-espresso/5.0.2. I ran
an scf calculation using an LDA norm conserving pseudo potential
(C.pz-vbc.UPF). I found an optimised lattice parameter of 4.698 (Bohr)
using a vc-relax calculation. I then ran an scf with the optimised
lattice parameter and ecutwfc. I then proceeded onto producing a band
structure with the following k-points in units of 2pi/a (Gamma (0,0,0)
- K (0.33333, 0.57735027, 0) - M (0.5, 0.28867513, 0)). The band
structure agrees with literature, where the dirac points meet at the K
point. I then moved on to calculating the phonon at each k (or
q) point. I ran the scf calculation once again in a new directory, I
ran the phonon at gamma, K, and M. the results seemed to agree
with literature. However, when I ran the phonon dispersion
calculation, the results go all over the place. The gamma k and m
points are the same but the curve is not expected. Obviously, after
running the ph.x I ran a q2r.x calculation, followed by a matdyn.x
calculation. To be clear I checked my k-points, I checked the k-path,
the mp grid I used was 12x12x1 when calculating the phonon
dispersion and 48x48x1 when running an scf calculation. Also, to
clarify I did the tutorial for Al and Si and produced correct
plots. Below are my input files:
------------------------------------------------------------------------------------------------------------------------------------
-------- SCF
---------------------------------------------------------------------------------------------------------------------
&CONTROL
prefix = 'graphene'
pseudo_dir = '/home/fa2215/bin/upf_files'
calculation = 'scf'
restart_mode = 'from_scratch'
verbosity = 'high'
tprnfor = .TRUE.
tstress = .TRUE.
etot_conv_thr = 1.0D-4
forc_conv_thr = 1.0D-3
nstep = 50000
wf_collect = .TRUE.
/
&SYSTEM
ibrav = 4
celldm(1) = 4.698
celldm(3) = 18.616
nat = 2
ntyp = 1
nbnd = 10
ecutwfc = 110
ecutrho = 440
occupations = 'smearing'
smearing = 'mp'
degauss = 0.1
/
&ELECTRONS
diagonalization = 'david'
electron_maxstep = 1000
conv_thr = 1.0e-8
mixing_beta = 0.3
/
ATOMIC_SPECIES
C 12.01 C.pz-vbc.UPF
ATOMIC_POSITIONS crystal
C 0.6666666666 0.3333333333 0.0000000000
C 0.3333333333 0.6666666666 0.0000000000
K_POINTS (automatic)
48 48 1 0 0 0
------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------
------ PHONON
---------------------------------------------------------------------------------------------------------------------
Phonon Dispersion of graphene
&inputph
tr2_ph=1.0d-12
ldisp=.true.
nq1=12 nq2=12 nq3=1
prefix='graphene'
amass(1)=12.01
outdir='/work/fa2215/Computational_Data/Graphene/Flat_Graphene/NM_PZ_LDA/Phonon_Calc/Disp/Disp2'
fildyn='graphene.dyn'
/
------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------
----------- Q2R
--------------------------------------------------------------------------------------------------------------------
&input
fildyn='graphene.dyn', zasr='crystal', flfrc='graphene.fc'
/
------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------
-------- MATDYN
-------------------------------------------------------------------------------------------------------------------
&input
asr='crystal'
amass(1)=12.01
flfrc='graphene.fc'
flfrq='graphene.freq'
/
219
0.000000 0.000000 0.000000 1.0
: : : :
------------------------------------------------------------------------------------------------------------------------------------
So to recap my procedure was as follows:
scf
phonon disp
q2r
matdyn
Let me know if anything is unclear and thank you for your help!
Best,
Faris
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