Re: [QE-users] I have failed to reproduce phonon dispersion of graphene

Evgenii Tue, 30 Mar 2021 07:59:02 -0700

Dear Vahid,

If we use the default values of the q_in_band_form variables, then how do we find intermediate points between the points of high symmetry, as for example on this site https://www.afs.enea.it/buonocor/graphane-with-phonon.html ? Are intermediate points always needed, we noticed that in some examples they are missing.

Thanks for the help.

Evgeniy Sysoev

30.03.2021, 17:28, "Vahid Askarpour" <vh261...@dal.ca>:

The coordinates of the high-symmetry points in matdyn.in should be in cartesian not crystal because you are specifying q_in_band_form=.true.

Cheers,

Vahid

Vahid Askarpour
Department of physics and atmospheric science
Dalhousie University
Halifax, NS
CANADA

On Mar 30, 2021, at 11:19 AM, Evgenii <eisyso...@stud.eltech.ru> wrote:

CAUTION: The Sender of this email is not from within Dalhousie.

Dear Quantum Espresso experts,

I am having trouble calculating the phonon bands of graphene.

First, I took the cif-file of the already relaxed graphite cell from the Materials Project site https://next-gen.materialsproject.org/ and made graphene cell from it by hand.

Then I relaxed the cell obtained with vc-relax and 12x12x1 k-point set.

I used the same parameters to perform a scf calculation:

&CONTROL

calculation='scf'

title='graphene'

prefix='graphene'

verbosity='high'

restart_mode='from_scratch'

nstep=1000

iprint=1

tstress=.true.

tprnfor=.true.

disk_io='default'

pseudo_dir = '/home/mxm2/Desktop/Graphene',

outdir='/home/mxm2/Desktop/Graphene/temp'

/

&SYSTEM

ibrav = 0,

celldm(1)=1.889726,

nat = 2,

ntyp = 1,

ecutwfc = 60.0 ,

ecutrho = 480.0 ,

/

&ELECTRONS

electron_maxstep = 1000,

conv_thr = 1.0d-12 ,

mixing_mode = 'plain' ,

mixing_beta = 0.7d0 ,

/

ATOMIC_SPECIES

C 12.011 C.pz-rrkjus.UPF

ATOMIC_POSITIONS (crystal)

C 0.000000000 0.000000000 0.000861580

C 0.333333000 0.666667000 0.000838420

CELL_PARAMETERS (alat)

2.438515837 -0.000000000 0.000000000

-1.219257919 2.111816662 0.000000000

-0.000000000 -0.000000000 19.995916314

K_POINTS automatic

12 12 1 0 0 0

Then, I run ph.in calculation:

&inputph

recover=.true.

tr2_ph=1.0d-14,

prefix='graphene',

ldisp=.true.

nq1=12,

nq2=12,

nq3=1,

amass(1)=12.011,

outdir='/home/mxm2/Desktop/Graphene/temp',

fildyn='graphene.dyn',

/

My q2r:

&input

fildyn='graphene.dyn',

zasr='simple',

flfrc='graphene.12x12x1.fc'

/

Matdyn input:

&input

asr='simple',

amass(1)=12.011,

flfrc='graphene.12x12x1.fc',

flfrq='graphene.disp.freq'

q_in_band_form=.true.,

/

4 ! number of q-points

0.000 0.000 0.000 10 ! gamma point

0.500 0.000 0.000 10 ! M

0.333 0.333 0.000 10 ! K

0.000 0.000 0.000 1 ! gamma point

Plotband:

graphene.disp.freq

0 1600

graphene.disp.freq.dat

graphene.disp.freq.ps

0

100 0

Why the phonon dispersion does not match the pictures from the papers and for calculations with e.g. 18x18x1 k-point and nq-point sets the output file of graphene.dyn1 look like:

Dielectric Tensor:

************************ 166.332153320312 0.000000000000

166.332275390625************************ 0.000000000000

0.000000000000 0.000000000000 1.116060253916

Effective Charges E-U: Z_{alpha}{s,beta}

atom # 1

-11117471.575740195811 -0.002632206306 0.000000000000

-0.002632205375-11117471.579664016142 0.000000000000

0.000000000000 0.000000000000 -0.003734609171

Also, what is the best way to set the lattice parameters, via Ibrav or CELL_PARAMETERS?

Any help is appreciated.

Best regards,

Evgeniy Sysoev.

<graphene.disp.freq.jpg>_______________________________________________
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,
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list users@lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users

_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list users@lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users

Re: [QE-users] I have failed to reproduce phonon dispersion of graphene

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