[QE-users] wrong phonon dispersion at K-point

[Roozbeh Anvari]

Dear Vahid,

Thank you for your help,
changing *q_in_band_form=.true* to *q_in_cryst_coord*=.true resolves the
problem as you suggested,

Cheers
Roozbeh
PDF, Physics, Queen's university



On Sat, Jan 23, 2021 at 12:56 AM Roozbeh Anvari <roozbeh.anvari at gmail.com>
wrote:

>
>
> Dear Quantum Espresso experts,
>
> I am having a trouble calculating the phonon bands of graphene at
> $K$-point,
>
> I am using NC+LDA and NC+PBE, ecutwfs=60, Ecutrho=400.0,
> forc_conv_thr=1.0d-6,
>
> as you can see in the attached figure, the calculated acoustic and optical
> eigenvalues are ok at $\Gamma$ and $M$-points, however the calculated value
> deviates from what it should be at $K$-point:
> TA and ZA branches are not overlapping at $K$-point,
> and a strange bump can be seen when ZO approaches $K$-point,
>
> I have checked the convergence for K-mesh, Ecutwfs, and Ecutrho,
> I have also tried increasing the K and q mesh for scf-calculation,
> using tr2_ph = 1E-14 and alpha_mix(niter)= .1 also does not improve the
> results,
>
>
> Thank you for your help,
> Regards,
> Roozbeh
> PDF, physics, Queen's university
>
>
> Here is the setup I am using,
>
>     step 1, pw.x
>
>     &CONTROL
>     ....
>      calculation='scf'
>      forc_conv_thr=1.0d-6,
>     /
>
>     &SYSTEM
>     ibrav=0, nat = 2, ntyp = 1,
>     ecutwfc = 60.0 , ecutrho = 400.0, ! 480
>     nosym=.true.,
>     occupations='smearing', smearing='cold', degauss=0.02
>     la2F = .true.,
>    /
>
>     &ELECTRONS
>     startingwfc='random'
>     diagonalization='cg'
>     conv_thr = 1.0e-12
>     mixing_beta = 0.2
>     electron_maxstep=200
>
>
>     ATOMIC_SPECIES
>     C  12.011   C.pz-vbc.UPF
>
>     CELL_PARAMETERS (angstrom)
>        2.428479517  -0.000000605   0.000000000
>       -1.214240282   2.103124989   0.000000000
>        0.000000000   0.000000000  20.000000000
>
>     ATOMIC_POSITIONS (crystal)
>     C            -0.0002315717        0.0002344099        0.4996978700
>     C             0.6664267343        0.3335704066        0.4996978902
>
>     K_POINTS automatic
>     64 64  1 0 0 0
>
>     %--------------------
>     %      step 2 ,pw.x
>     %--------------------
>
>   same as above except
>   la2F = .false.,
>    K_POINTS automatic
>     32 32 1 0 0 0
>
>     %--------------------
>     %      step 3 , ph.x
>     %--------------------
>
>
>      &inputph
>       tr2_ph=1.0d-14,
>       prefix='ml_gr',
>       fildvscf='ml_gredv',
>       amass(1)=12.011,
>       outdir='./tmp',
>       fildyn='ml_gr.dyn',
>       electron_phonon='interpolated',
>       !el_ph_sigma=0.005,
>       !el_ph_nsigma=10,
>       alpha_mix=0.1
>       diagonalization='cg',
>       trans=.true.,
>       ldisp=.true.,
>       nq1=4 , nq2=4, nq3=1
>       ! nq1=8 , nq2=8, nq3=1   makes no difference
>      /
>
>
>     %--------------------
>     %      step 4  , q2r.x
>     %--------------------
>
>      &input
>       zasr='simple',
>       fildyn='ml_gr.dyn',
>       flfrc='gr333.fc',
>       la2F=.true.
>      /
>
>
>     %--------------------
>     %      step 5 , matdyn.x
>     %--------------------
>
>       &input
>         asr='simple',
>         amass(1)=12.011,
>         flfrc='gr333.fc',
>         flfrq='gr333.freq',
>         la2F=.true.,
>         dos=.false.
>          q_in_band_form=.true.
>  /
>        4
>         0 0 0 20
>         0 .5 0 20
>        -0.3333333  0.6666666  0. 20
>         0 0 0 1
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20210123/9a575ebf/attachment.html>