[Pw_forum] Monolayer WSe2 band structure related problems

[Ari P Seitsonen]

Dear Anindya Bose,

   How does your input now look like? That you were able to run 'vc-relax' 
but after that the self-consistent loop does not converge sounds weird.

   I usually use 'local-TF' as the mixing mode in systems with vacuum.

     Greetings,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Tue, 7 Mar 2017, Anindya Bose wrote:

> I have done my vc-relax successfully but while performing scf calculation I am getting an error: convergence is not achieved in 100 steps.Please
> help me in this issue.I have made ecutwfc=60.How to resolve this error.How can I converge my process.
> 
> regards,
> Anindya Bose
> 
> On Mon, Mar 6, 2017 at 10:34 PM, Ari P Seitsonen <Ari.P.Seitsonen at iki.fi> wrote:
>
>       Dear Anindya,
>
>         Please provide your affiliation - to respect the other subscribers of the forum (please go through the instructions on how to post
>       to the forum).
>
>         Adding to the other items mentioned in the previous responses, I would like to point out that apparently you want to relax the
>       lateral lattice constant of the cell, but without further options also the vertical lattice constant is optimised, and probably the
>       vacuum is either reducing or increasing (it never goes to zero, due to numerical precision if nothing else; also the DFT+D2 dispersion
>       correction has a long tail): Please check the input option 'cell_dofree'.
>
>         'cell_factor = 15' does not make much sense; your threhould variables 'etot_conv_thr' and 'forc_conv_thr' look very loose to me. Are
>       you sure about "disk_io = 'high'"?
>
>           Greetings,
>
>              apsi
>
>       -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
>         Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
>           Ecole Normale Supérieure (ENS), Département de Chimie, Paris
>           Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935
> 
>
>       On Mon, 6 Mar 2017, Anindya Bose wrote:
>
>             Dear Sir,
>             I have used this code but I didn't get the direct band gap structure of monolayer WSe2.
>             &CONTROL
>               calculation='vc-relax',
>               outdir='monolayer WSe2',
>               prefix='calc',
>               pseudo_dir='/home/anindya/Desktop/pseudopotential',
>               verbosity='high',
>               disk_io='high',
>               wf_collect=.true.,
>               nstep = 50,
>               etot_conv_thr=1d-02,
>               forc_conv_thr=1d-02,
>             /
>
>             &SYSTEM
>               ibrav=4,
>               celldm(1)=6.2020811408d0, celldm(3)=4.3566118221d0,
>               nat=3,
>               ntyp=2,
>               ecutwfc=40.0d0,
>               ecutrho =130.0d0,
>               nbnd=200,
>               vdw_corr='Grimme-D2',
>               force_symmorphic=.true.,
>               input_dft='PBE',
>               occupations='fixed',
>             /
>
>             &ELECTRONS
>               diagonalization='david',
>               conv_thr=1d-08,
>               mixing_mode='plain',
>               mixing_beta=0.700d0,
>             /
>
>             &ions
>               ion_dynamics ='bfgs',
>             /
>              
>             &cell
>               cell_dynamics ='bfgs',
>               cell_factor=15,
>             /
>
>             ATOMIC_SPECIES
>               Se 78.960000d0 Se_ONCV_PBE-1.0_r.oncvpsp.upf
>               W 183.840000d0 W_ONCV_PBE-1.1_r.oncvpsp.upf
>
>             ATOMIC_POSITIONS {alat}
>               W    0.5000000000d0   0.2886751346d0   2.1782995738d0
>               Se   0.5000000000d0  -0.2886751346d0   1.6692977456d0
>               Se   0.5000000000d0  -0.2886751346d0   2.6873014019d0
>
>             K_POINTS {automatic}
>               10 10 1 0 0 0
>
>             I have enclosed my output band structure with this mail.Can you please help me in this regard.How can I get the correct
>             band diagram of monolayer
>             WSe2(direct bandgap). I have used all the codes for spin calculation and I got the spin orbit coupling but didn't find
>             perfect band diagram.I will
>             be waiting for your response.
> 
> 
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> 
>