[Pw_forum] Comments on Graphene on BN relaxation
Ngoc Linh Nguyen
nnlinh at sissa.it
Wed Jan 27 09:22:01 CET 2010
mohamed sabri majdoub wrote:
> Dear Linh,
>
> I am trying to understand what you just explain.
> If I keep the bottom and middle layer fixed (BN layers) and I only
> translate the third layer on the top of them (graphene) by an amount
> corresponding to the interlayer increase d. For example delta d =0.1 Ang.
> Originally, the interlayer distance is for example d=3.3 Ang is
> increased to 3.4 Ang by moving top layer up by 0.1 Ang and increasing
> the supercell size in the z direction by 0.1 Ang. I mean adding 0.1
> Ang more vacuum on the top layer to keep a vacuum distances on the top
> graphene and bottom BN layer of 8 Ang for each side.
> Is it the right way?
Yes, it is
> Thank you very much for your help.
>
> On Tue, Jan 26, 2010 at 1:00 PM, Ngoc Linh Nguyen <nnlinh at sissa.it
> <mailto:nnlinh at sissa.it>> wrote:
>
> mohamed sabri majdoub wrote:
> > Dear Linh,
> >
> > Thank you for your response.
> > So, do you suggest that I should increase the supercell size (by the
> > same amount of d increase) each time I increase the value of d?
> You should do that if d values change by moving 1st and 3rd layer and
> keep middle layer.
> Somehow, let try to keep away the interactions of the layers between
> neighbor supercells.
> > Thanks,
> >
> > On Tue, Jan 26, 2010 at 11:02 AM, Ngoc Linh Nguyen
> <nnlinh at sissa.it <mailto:nnlinh at sissa.it>
> > <mailto:nnlinh at sissa.it <mailto:nnlinh at sissa.it>>> wrote:
> >
> > > When I plot the graph, it looks like ecutwfc =60 is
> optimal. Is it
> > right? Is it the right way to do > it? Is the final energy
> (obtained
> > from last relaxation step) the right quantity?
> > I think what you did for checking E vs. ecutwfc is right.
> However,
> > with
> > the big model it could be quite expensive. You can do like
> that: you
> > choose an ecutwfc value firstly, for example ecutwfc = 40
> Ry, and
> > relax
> > your model with that value, then increase the value ecutwcf and
> > run scf
> > only, you can obtain a relation E vs. ecutwfc in similar.
> >
> > > For Final energy (obtained from last relaxation step) vs d
> > interlayer
> > distance at cutoff ecutwfc = 50.0:
> > > .... ecutwfc = 60.0
> > I am confusing about increasing of d values in your models.
> > If you keep the sizes of supercell unchanged, when
> increasing the
> > value of d, the 3rd layer of the above supercell and 1st
> layer of the
> > below supercell should be approached too close together, i.e. ,
> > let try
> > visualizing by Xcryden at different values of d. And it can
> reduce an
> > increase of energy of your models as d is lager.
> >
> > Good luck,
> > Linh
> > mohamed sabri majdoub wrote:
> > > Dear all,
> > >
> > > I run calculations of 1 layer of graphene on bilyaer boron
> nitride.
> > > I am trying to study the Energy vs cutoff and Energy vs
> interlayer
> > > distance d between the graphene layer and top of BN layer.
> > > I got the following results after several runs. Is it the
> right
> > way to
> > > do it?
> > > Here is the input file I am using:
> > >
> >
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> > > &control
> > > title = 'GphBN'
> > > calculation = 'relax'
> > > outdir = '/pwscf/pwscftemp'
> > > prefix = 'GphBN'
> > > pseudo_dir = '/pseudopot-C-B-N'
> > > tprnfor = .t.
> > > restart_mode = 'from_scratch'
> > > wf_collect = .true.
> > > disk_io = 'low'
> > > /
> > > &system
> > > ibrav = 0,
> > > celldm(1) = 1.8897261
> > > nat = 72,
> > > ntyp = 3,
> > > ecutwfc = 60.0
> > > occupations = 'smearing'
> > > smearing = 'gaussian'
> > > degauss = 0.003675
> > >
> > > /
> > > &electrons
> > > mixing_mode = 'local-TF'
> > > mixing_beta = 0.05
> > > diagonalization = 'david'
> > > conv_thr = 1.D-5
> > > /
> > > &ions
> > > trust_radius_ini = 0.10
> > >
> > > /
> > > &cell
> > >
> > > ATOMIC_SPECIES
> > > B 10.81100 B.pz-vbc.UPF
> > > C 12.01070 C.pz-vbc.UPF
> > > N 14.00674 N.pz-vbc.UPF
> > > ATOMIC_POSITIONS angstrom
> > > B 0.710000 8.607000 11.306000
> > > B 0.710000 11.066000 11.306000
> > > B 2.840000 7.377000 11.306000
> > > B 0.710000 6.148000 11.306000
> > > B 6.390000 6.148000 8.000000
> > > B 6.390000 8.607000 8.000000
> > > B 6.390000 11.066000 8.000000
> > > B 2.840000 9.836000 11.306000
> > > B 7.100000 7.377000 11.306000
> > > B 7.100000 9.836000 11.306000
> > > B 7.100000 12.295000 11.306000
> > > B 4.970000 11.066000 11.306000
> > > B 2.840000 12.295000 11.306000
> > > B 4.970000 6.148000 11.306000
> > > B 4.970000 8.607000 11.306000
> > > B 4.260000 7.377000 8.000000
> > > B 2.130000 11.066000 8.000000
> > > B 2.130000 8.607000 8.000000
> > > B 2.130000 6.148000 8.000000
> > > B 4.260000 9.836000 8.000000
> > > B 0.000000 7.377000 8.000000
> > > B 0.000000 9.836000 8.000000
> > > B 4.260000 12.295000 8.000000
> > > B 0.000000 12.295000 8.000000
> > > C 2.130000 6.148000 14.106000
> > > C 2.130000 8.607000 14.106000
> > > C 2.130000 11.066000 14.106000
> > > C 0.000000 12.295000 14.106000
> > > C 0.000000 9.836000 14.106000
> > > C 0.000000 7.377000 14.106000
> > > C 0.710000 11.066000 14.106000
> > > C 0.710000 8.607000 14.106000
> > > C 0.710000 6.148000 14.106000
> > > C 6.390000 8.607000 14.106000
> > > C 6.390000 6.148000 14.106000
> > > C 4.970000 11.066000 14.106000
> > > C 6.390000 11.066000 14.106000
> > > C 7.100000 12.295000 14.106000
> > > C 7.100000 9.836000 14.106000
> > > C 7.100000 7.377000 14.106000
> > > C 4.970000 8.607000 14.106000
> > > C 2.840000 12.295000 14.106000
> > > C 2.840000 9.836000 14.106000
> > > C 2.840000 7.377000 14.106000
> > > C 4.260000 7.377000 14.106000
> > > C 4.970000 6.148000 14.106000
> > > C 4.260000 12.295000 14.106000
> > > C 4.260000 9.836000 14.106000
> > > N 0.000000 12.295000 11.306000
> > > N 0.000000 9.836000 11.306000
> > > N 0.000000 7.377000 11.306000
> > > N 2.840000 7.377000 8.000000
> > > N 2.840000 9.836000 8.000000
> > > N 2.840000 12.295000 8.000000
> > > N 4.970000 11.066000 8.000000
> > > N 4.970000 8.607000 8.000000
> > > N 4.970000 6.148000 8.000000
> > > N 7.100000 12.295000 8.000000
> > > N 7.100000 9.836000 8.000000
> > > N 7.100000 7.377000 8.000000
> > > N 0.710000 6.148000 8.000000
> > > N 0.710000 8.607000 8.000000
> > > N 0.710000 11.066000 8.000000
> > > N 6.390000 11.066000 11.306000
> > > N 6.390000 8.607000 11.306000
> > > N 6.390000 6.148000 11.306000
> > > N 2.130000 11.066000 11.306000
> > > N 2.130000 8.607000 11.306000
> > > N 2.130000 6.148000 11.306000
> > > N 4.260000 12.295000 11.306000
> > > N 4.260000 9.836000 11.306000
> > > N 4.260000 7.377000 11.306000
> > > K_POINTS automatic
> > > 10 10 1 1 1 0
> > > CELL_PARAMETERS
> > > 8.51980 0.00000 0.00000
> > > 0.00000 7.37600 0.00000
> > > 0.00000 0.00000 22.6120
> > >
> >
> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> > > The results are :
> > >
> > > 1- Final energy (obtained from last relaxation step) vs cutoff
> > (ecutwfc)
> > >
> > > cut20: Final energy = -857.6291985882 Ry
> > > cut30: Final energy = -876.5012327526 Ry
> > > cut40: Final energy = -885.4765196610 Ry
> > > cut50: Final energy = -890.0493283821 Ry
> > > cut60: Final energy = -892.0114549785 Ry
> > > cut70: Final energy = -892.8706506804 Ry
> > > cut80: Final energy = -893.2520149989 Ry
> > >
> > > When I plot the graph, it looks like ecutwfc =60 is
> optimal. Is it
> > > right? Is it the right way to do it? Is the final energy
> (obtained
> > > from last relaxation step) the right quantity?
> > >
> > >
> >
> ------------------------------------------------------------------------------------------------------------------------------------------------------------
> > > 2- For Final energy (obtained from last relaxation step) vs d
> > > interlayer distance at cutoff ecutwfc = 60.0:
> > >
> > > d=2.5= Final energy = -892.0122348924 Ry
> > > d=3.0= Final energy = -892.0119194861 Ry
> > > d=3.1= Final energy = -892.0089055437 Ry
> > > d=3.2= Final energy = -892.0104083862 Ry
> > > d=3.3= Final energy = -892.0115677649 Ry
> > > d=3.4= Final energy = -892.0113018510 Ry
> > > d=3.5= Final energy = -892.0121118001 Ry
> > > d=3.6= Final energy = -892.0113544429 Ry
> > > d=3.7= Final energy = -892.0096184164 Ry
> > > d=3.9= Final energy = -892.0041914533 Ry
> > >
> > > There are fluctuations in the data? Is it normal?
> > >
> >
> -----------------------------------------------------------------------------------------------------------------------------------------------------
> > >
> > > 3- For Final energy (obtained from last relaxation step) vs d
> > > interlayer distance at cutoff ecutwfc = 50.0:
> > >
> > > d=2.5= Final energy = -890.0504214490 Ry
> > > d=2.8= Final energy = -890.0503533642 Ry
> > > d=2.9= Final energy = -890.0503471460 Ry
> > > d=3.0= Final energy = -890.0486572147 Ry
> > > d=3.1= Final energy = -890.0491375298 Ry
> > > d=3.2= Final energy = -890.0480863744 Ry
> > > d=3.3= Final energy = -890.0492074574 Ry
> > > d=3.4= Final energy = -890.0501303488 Ry
> > > d=3.6= Final energy = -890.0488317041 Ry
> > > d=3.5= Final energy = -890.0492797825 Ry
> > > d=3.7= Final energy = -890.0470527582 Ry
> > > d=3.8= Final energy = -890.0443250729 Ry
> > > d=3.9= Final energy = -890.0412177248 Ry
> > >
> > > Same thing for these data.
> > > Is there any thing wrong?
> > > Your suggestions are welcomed.
> > >
> > > Thank you in advance for your help!
> > >
> > > Regards,
> > >
> > > ME
> > > University of Houston
> > >
> > >
> > >
> > >
> > >
> >
> ------------------------------------------------------------------------
> > >
> > > _______________________________________________
> > > Pw_forum mailing list
> > > Pw_forum at pwscf.org <mailto:Pw_forum at pwscf.org>
> <mailto:Pw_forum at pwscf.org <mailto:Pw_forum at pwscf.org>>
> > > http://www.democritos.it/mailman/listinfo/pw_forum
> > >
> >
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org <mailto:Pw_forum at pwscf.org>
> <mailto:Pw_forum at pwscf.org <mailto:Pw_forum at pwscf.org>>
> > http://www.democritos.it/mailman/listinfo/pw_forum
> >
> >
> >
> ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org <mailto:Pw_forum at pwscf.org>
> > http://www.democritos.it/mailman/listinfo/pw_forum
> >
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org <mailto:Pw_forum at pwscf.org>
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
More information about the users
mailing list