[Pw_forum] is there any correction needed ?? any changes can be done for the fast calculation of relax ???

[Giovanni Cantele]

I’m posting the answer to the forum, it is always much more effective than private messages, there are much more people that might
help you and maybe give you more suggestions than I’m able to do…. ;-)

it seems you’re trying to study a single graphene sheet. If this is the case, two periodic replicas are separated by
~ 18 A ( = celldm(3) x celldm(1) x 0.529177 ), you could try to reduce such distance down to 10 A, that should be enough to
prevent periodic replicas from interacting with each other. Also, a 16x16x1 grid seems to be quite large, you might start with 4x4x1
and then check convergence with 6x6x1 and 8x8x1 (and go beyond only if you see that some property you are interested in is not well converged).

For sure this reduces a lot the size of your calculation and its memory requirements. In addition, just to better identify your problem, did you notice any error message 
(either quantum-espresso or operating system related) in the output file???? (things like segmentation fault, ….)

Giovanni




> On 12 Jul 2017, at 10:57, Shishir Timilsena <expressgucci at gmail.com> wrote:
> 
> &control
>     calculation='scf'
>     restart_mode='from_scratch'
>     prefix='graphenescf'
>     outdir='/home/physics/Downloads/shishir'
>     pseudo_dir = '/home/physics/Downloads/shishir',
>     tstress=.true.
>     tprnfor=.true.
>     verbosity='high'
>     forc_conv_thr=1.0d-3
>     etot_conv_thr=1.0d-4
>  /
>  &SYSTEM
>  ibrav=4
>  celldm(1)=4.65
>  celldm(3)=7.3
>  nat=2
>  ntyp=1
>  ecutwfc=45
>  ecutrho=450
>  vdw_corr='dft-d'
>  occupations='smearing'
>  smearing='mv'
>  degauss=0.002
> /
>  &ELECTRONS
>  diagonalization='david'
>  mixing_mode='plain'
>  electron_maxstep = 100,
>  conv_thr = 1.0D-8,
>  mixing_beta=0.6
>  /
>  ATOMIC_SPECIES
>  C 12.011 C.pbe-rrkjus.UPF
> 
> ATOMIC_POSITIONS (angstrom)
>  C 0.000000000 0.000000000 0.000000000
>  C 1.232850116 0.706423116 0.000000000
> 
>  K_POINTS {automatic}
>  16 16 1 0 0 0

-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.fisica.unina.it/~cantele

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