[Pw_forum] Monolayer WSe2 band structure related problems

[Anindya Bose]

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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