[Pw_forum] ESM and ESM_w
Minoru Otani
minoru.otani at aist.go.jp
Tue Aug 4 09:19:05 CEST 2015
Dear Nkosinathi,
Please remember that the ESM is nothing special. It’s just a slab calculation.
So, first, you need to make a good slab geometry. ideally, the thickness of the vacuum
layer must be large enough for two successive slabs not to interact significantly.
I think your vacuum is too thin. The following reference is a good example for how to
prepare a slab geometry:
PHYSICAL REVIEW B 70, 155417 (2004)
(They concluded that 20 a.u. thick vacuum is enough for their slab calculation. this is
comparable to my tips #1)
Using the esm_bc=bc1, you can get two work functions for both surfaces (Al & water).
At least you have to obtain the Al work function comparable to an experiment (or a reliable calculation).
Since the work function of the water side is an instantaneous one, it is difficult to discuss
the validity of the value. But if you calculate time average of those value, you can
obtain the Volta potential difference of the Al/H2O interface. (see, equation A-2 in J. Phys. Soc.
Jpn. 77, 024802 (2008))
Best,
Minoru
-------------------------------------------------------------
Minoru Otani
Nanomaterials Research Institute (NRI),
National Institute of Advanced Industrial
Science and Technology (AIST)
e-mail：minoru.otani at aist.go.jp
Phone : +81-29-861-5202
-------------------------------------------------------------
On Aug 3, 2015, at 7:14 PM, Nkosinathi Malaza <nuttymalaza at gmail.com> wrote:
> Hi All,
>
> For the system I explained above, for the ESM=bc1 and pbc the system converges except when I use bc2 and bc3 with ESM_w=0.25 the system does not converge even when there is no ESM_w the system for bc2 and bc3 does not converge. PLease assist.
>
> Best
> Nkosinathi
>
> On Thu, Jul 30, 2015 at 3:40 PM, Minoru Otani <minoru.otani at aist.go.jp> wrote:
> Dear Nkosinathi,
>
> Please make sure the following points.
> 1. Do you have sufficient vacuum thickness on both side?
> Typically we need 5-8 angstrom thickness on each (thus, 10-16 A in total)
> 2. The centre of the slab (Al/H2O) is located around z=0?
> 3. Can you get a converged result with periodic boundary condition?
>
> Best regards,
> Minoru
>
> -------------------------------------------------------------
> Minoru Otani
> Nanomaterials Research Institute (NRI),
> National Institute of Advanced Industrial
> Science and Technology (AIST)
> e-mail：minoru.otani at aist.go.jp
> Phone : +81-29-861-5202
> -------------------------------------------------------------
>
> On Jul 30, 2015, at 10:06 PM, Nkosinathi Malaza <nuttymalaza at gmail.com> wrote:
>
> > Hi Bahadir,
> >
> > It does the same, the changes did not work as I have the same output file.
> >
> > Best
> >
> >
> >
> > On Thu, Jul 30, 2015 at 11:40 AM, Nkosinathi Malaza <nuttymalaza at gmail.com> wrote:
> > Thank you so much, I will implement the changes and get back to you. Thank you again for the assistance.
> >
> >
> > Best
> > Nkosinathi
> >
> > On Thu, Jul 30, 2015 at 11:36 AM, Bahadır salmankurt <bsalmankurt at gmail.com> wrote:
> > *******************************
> > &control
> > calculation = 'scf',
> > restart_mode ='from_scratch',
> > prefix = 'Al111',
> > pseudo_dir = '.',
> > outdir = './work/',
> > tprnfor = .true.,
> >
> > /
> > &system
> > ibrav= 0,
> > nat = 123,
> > ntyp = 3,
> > ecutwfc = 60.0,
> > ecutrho = 600,
> > occupations = 'smearing',
> > smearing = 'mp',
> > degauss = 0.02,
> >
> > nbnd=210 !! you may use this.
> > assume_isolated='esm',
> > esm_bc='bc3'
> > esm_w = 0.0,
> > nosym = .TRUE.
> > /
> > &electrons
> >
> > mixing_beta = 0.1,
> > mixing_mode='local-TF'
> > conv_thr=1.d-8
> > electron_maxstep=100 ! default is a=100. your calculation stoped after 100 iter. also u can change if u want
> > /
> >
> > ATOMIC_SPECIES
> > Al 26.9815 Al.pbe-rrkj.UPF
> > O 15.9994 O.pbe-rrkjus.UPF
> > H 1.00794 H.pbe-rrkjus.UPF
> >
> > CELL_PARAMETERS angstrom
> > 8.589862 0.000000 0.000000
> > 4.294931 7.439039 0.000000
> > 0.000000 0.000000 23.675729
> >
> > ***********************
> > Dear Nkosinathi,
> >
> > I pointed out the thinks that you can change.
> >
> > hope this works
> >
> > bests
> > bahadir
> >
> >
> >
> >
> >
> >
> >
> >
> > 2015-07-30 11:51 GMT+03:00 Nkosinathi Malaza <nuttymalaza at gmail.com>:
> > Hi Bahadir,
> >
> > Thank you for assistance, I have attached the input file.
> >
> > Kind regards
> > N. Malaza
> >
> > On Thu, Jul 30, 2015 at 9:38 AM, Bahadır salmankurt <bsalmankurt at gmail.com> wrote:
> > Dear Nkosinathi,
> >
> > It seems the problem occured in iterations. Can you give us input file?
> >
> > pls reduce mixing_beta to 0.3 or lower. also change mixing_mode to local_TF and add a few extra bands.
> >
> > bests
> > Bahadir
> >
> > 2015-07-30 9:48 GMT+03:00 Nkosinathi Malaza <nuttymalaza at gmail.com>:
> > Dear family,
> >
> > I want to introduce the ESM and ESM_w on a supercell of 123 Al-H2O atoms. When I do introduce the ESM on the system it does not finish running.
> >
> > I have attached the output file.
> >
> > Kind regards
> > N. Malaza
> >
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