[Pw_forum] Pw_forum Digest, Vol 17, Issue 32

Mon Nov 17 04:46:14 CET 2008

Dear Prof.Eyvaz Isaev,
Thanks for your reply.
I have looked into the user guide and got the impression that the warning I am getting willnot seriously affect further calcualtions.
regards
Assa Aravindh.S
Research Scholar
Theory and Computational Studies Section
Material Science Division
Indira gandhi Centre for Atomic Research 
Kalpakkam - 603102, India

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Subject: Pw_forum Digest, Vol 17, Issue 32

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Today's Topics:

   1. Re: (no subject) (Eyvaz Isaev)
   2. Re: convergence problem (Eyvaz Isaev)
   3. sawtooth method (hanghui chen)
   4. a possible problem in the routine add_efield.f90 (hanghui chen)

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Message: 1
Date: Sat, 15 Nov 2008 04:46:41 -0800 (PST)
From: Eyvaz Isaev <eyvaz_isaev at yahoo.com>
Subject: Re: [Pw_forum] (no subject)
To: pw_forum at pwscf.org
Message-ID: <901139.66497.qm at web65712.mail.ac4.yahoo.com>
Content-Type: text/plain; charset=us-ascii

Dear Fereydoon,

Already you have it. Please see /examples/example03 with Al(001) slab. Besides, you need to read some papers how to deal with such kind calculations. For example, Payne et al. in Review of Modern Physics, vol. 64, p.1045 (1992).
There are also textbooks "Surface Physics" of Zengwil, and "Principles of Surface Physics" by Bechstedt.

Please also do not forget specify your affiliation as it is default in this forum.

Bests,
Eyvaz. 

-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden 
Condensed Matter Theory Group, Uppsala University, Sweden 
Eyvaz.Isaev at fysik.uu.se, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com

--- On Sat, 11/15/08, fereydoon khazali <frnkhzi at yahoo.com> wrote:

> From: fereydoon khazali <frnkhzi at yahoo.com>
> Subject: [Pw_forum] (no subject)
> To: Pw_forum at pwscf.org
> Date: Saturday, November 15, 2008, 8:56 AM
> All dear 
> Please send me an input file for slab.
> thanks
> 
> 
>       _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum

------------------------------

Message: 2
Date: Sat, 15 Nov 2008 05:04:14 -0800 (PST)
From: Eyvaz Isaev <eyvaz_isaev at yahoo.com>
Subject: Re: [Pw_forum] convergence problem
To: PWSCF Forum <pw_forum at pwscf.org>
Message-ID: <262570.76464.qm at web65712.mail.ac4.yahoo.com>
Content-Type: text/plain; charset=us-ascii

Dear Asa,

I think you can trust these results. Please have a look at Troubleshooting in User's Guide: "warning : N eigenvectors not converged ..."

We appreciate if you will specify your affiliation.

Bests,
Eyvaz.

-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden 
Condensed Matter Theory Group, Uppsala University, Sweden 
Eyvaz.Isaev at fysik.uu.se, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com

--- On Sat, 11/15/08, asa aravindh <asaaravindh at yahoo.co.in> wrote:

> From: asa aravindh <asaaravindh at yahoo.co.in>
> Subject: [Pw_forum] convergence problem
> To: pw_forum at pwscf.org
> Date: Saturday, November 15, 2008, 9:26 AM
> Dear all..
> I was trying to do scf and nscf calculations on ZnO
> nanowires using pwscf
> scf has run successfully, while nscf shows this warning in
> between..
>  Band Structure Calculation
>      CG style diagonalization
>      c_bands:  2 eigenvalues not converged
> .....................................
> but the code works even after this and finishes the nscf
> run. After looking into the forum I got the impression that
> this might be due to the algorithm "david", which
> I was using .So I changed to "CG" . Again the same
> situation is repeating. 
> My question is whether my results will be accurate if this
> warnig persists??
> If I do further calculations like transport taking this scf
> and nscf outputs how far my calculations will be reliable??
> can anybody please help me in this regard...........
> Thanks in advance
> asa
> 
> 
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------------------------------

Message: 3
Date: Sat, 15 Nov 2008 13:27:53 -0500
From: "hanghui chen" <chenhanghuipwscf at gmail.com>
Subject: [Pw_forum] sawtooth method
To: pw_forum at pwscf.org
Message-ID:
    <22ae3ca40811151027s7cfd5c64m3336acc7706cbc0d at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Dear PWSCF users,
      I calculate a symmetric STO slab (separated by vacuum) and turn on a
symmetric sawtooth potential (the turning point is right at the center of
the STO slab). I fix all the atoms. Without the sawtooth potential, the
forces are symmetric and there are no forces in the central layer. However,
when I turn on the sawtooth potential which I set to be symmetric, the
forces on the atoms are NO longer symmetric and the forces in the layer are
NO longer zero. The input file and the forces (turning on sawtooth
potential) are given below.
     Why are the forces NOT symmetric but the configuration (including the
sawtooth potential) is symmetric? Does the turning point in the material
cause any anomaly?
     Thank you very much.

Hanghui Chen
Department of Physics, Yale University

Input file:
&CONTROL
  calculation='scf'
  wf_collect=.true.
  pseudo_dir = './psp'
  outdir='.'
  wfcdir='/scratch'
  prefix='test1'
  disk_io='low'
  verbosity='high'
  tprnfor = .true.
  tstress = .true.
  dt=80.D0
  tefield=.true.
/
&SYSTEM
  ibrav=  6
  celldm(1) = 7.27
  celldm(3) = 6.0
  nat=  12
  ntyp= 3
  ecutwfc = 30.0
  ecutrho = 180.0
  occupations='smearing'
  smearing='gauss'
  degauss=0.005
  edir=3
  emaxpos=0.5
  eopreg=0.5
  eamp=0.01
/
&ELECTRONS
  diagonalization='david'
  mixing_beta = 0.7D0
  diago_david_ndim = 4
  mixing_mode= 'local-TF'
  electron_maxstep = 300
  startingpot = 'file'
  conv_thr= 1.d-8
/
&IONS
  ion_dynamics = 'bfgs'
  phase_space = 'full'
  pot_extrapolation = 'first_order'
  wfc_extrapolation = 'first_order'
/
&CELL
  cell_dynamics = 'damp-w'
/
ATOMIC_SPECIES
Sr  87.62  038-Sr-ca-sp-vgrp.uspp.format.UPF
Ti  47.90  022-Ti-ca-sp-vgrp.uspp.format.UPF
O   16.00  008-O-ca--vgrp.uspp.format.UPF
ATOMIC_POSITIONS alat
Sr 0.00 0.00 2.00
O  0.50 0.50 2.00
Ti 0.50 0.50 2.50
O  0.50 0.00 2.50
O  0.00 0.50 2.50
Sr 0.00 0.00 3.00
O  0.50 0.50 3.00
Ti 0.50 0.50 3.50
O  0.50 0.00 3.50
O  0.00 0.50 3.50
Sr 0.00 0.00 4.00
O  0.50 0.50 4.00
K_POINTS {automatic}
8 8 1 0 0 0
Forces:
atom   1 type  1   force =     0.00000001   -0.00000001   -0.09670746
atom   2 type  3   force =     0.00000000    0.00000000   -0.21698818
atom   3 type  2   force =     0.00000000    0.00000001   -0.17490285
atom   4 type  3   force =     0.00000000    0.00000000   -0.17341486
atom   5 type  3   force =     0.00000001    0.00000000   -0.17341491
atom   6 type  1   force =    -0.00000002    0.00000000    0.06540405
atom   7 type  3   force =    -0.00000001   -0.00000001   -0.01253063
atom   8 type  2   force =     0.00000001    0.00000001    0.32344891
atom   9 type  3   force =     0.00000000    0.00000000    0.08311003
atom  10 type  3   force =     0.00000000    0.00000000    0.08311005
atom  11 type  1   force =     0.00000000    0.00000000    0.16600421
atom  12 type  3   force =     0.00000001    0.00000000    0.12688164
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Message: 4
Date: Sun, 16 Nov 2008 01:27:57 -0500
From: "hanghui chen" <chenhanghuipwscf at gmail.com>
Subject: [Pw_forum] a possible problem in the routine add_efield.f90
To: pw_forum at pwscf.org
Message-ID:
    <22ae3ca40811152227m52d98444le4d554ea16b12600 at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Dear PWSCF users,
              In my previous email, I reported that if I calculated a
symmetric
   system (both the material and the external sawtooth potential are
   symmetric), I found that the forces are not symmetric. I think I may find
   the reason.
        The total force in the presence of sawtooth potential has two parts:
   one is from the variation of Kohn-Sham functional; the other is from
   sawtooth potential which in the code is "forcefield" (see the routine
   forces.f90). The additional force is calculated by the routine
   add_efield.f90. However in routine add_efield.f90, it only calculates the
   magnitude of the force but does not specify the direction (the additional
   force only has one direction).  Therefore all the forces in the 'reversed
   region' are not correctly calculated because the direction of
'forcefield'
   is NOT reversed as is the external electric field.
        I sincerely hope that the people who wrote the routine
add_efield.f90
   can reexamine the code and add the directions to the "forcefield".
        No offense intended.
        Thank you very much.
   Hanghui Chen
   Department of Physics, Yale University
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