[Pw_forum] Comments on Graphene on BN relaxation
mohamed sabri majdoub
majdoub at gmail.com
Tue Jan 26 19:20:19 CET 2010
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?
Thanks,
On Tue, Jan 26, 2010 at 11:02 AM, Ngoc Linh Nguyen <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
> >
> >
> >
> >
> > ------------------------------------------------------------------------
> >
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