[Pw_forum] Fermi energy in 'scf' and 'nscf'(XQ Wang)

[Stefano de Gironcoli]

Dear Haiping,
the ONLY Fermi energy that is meaningful is the one corresponding to a 
scf calculation... which is calculated  consistently with the 
corresponding  charge density.
All nscf or band calculations are performed  on grids which might  give 
non-regular sampling of the BZ...  you should not use the corresponding 
fermi energy .
stefano

lan haiping wrote:
> dear hande,
> i do wonder a point about fermi energy.
> when we draw a bands along high symmetry points, which
> values of fermi energy we should do align with ?  the situation of 
> 'nscf' calculation with large BZ sampling ,or just
> the 'bands' calculation along the high symmetry points ?
> Bests,
>
> On Wed, Aug 13, 2008 at 8:22 PM, Hande Ustunel 
>  > wrote:
>
> Dear Prasenjit,
>
> > If the difference in Fermi energy is quite large, what I would
> suggest is to
> > increase the no. of k-points in the nscf cal. & redo it.
>
> The fact that Guoying's nscf calculation was conducted along high
> symmetry
> points suggests that it was to be followed by a band structure
> run. In that
> case, it is not necessary to try to obtain a "good" Fermi energy
> from the
> nscf run other than convince oneself since this is not the point
> here. Besides, I don't think increasing the number of kpoints
> along these
> high symmetry directions would mean much because since you would
> still have
> a severely heterogeneous sampling. It should just sufficient to
> just draw
> the band structure from nscf along with the Fermi energy from the scf
> calculation. But you would be absolutely right if what we were
> trying to do
> here was to, say, increase resolution in a DOS plot.
>
> On a separate note, I suggest that you try bands rather than nscf
> if you
> are trying to draw a band structure since nscf worries about
> symmetries and
> creates extra points whereas bands just does the ones you ask it
> to do.
>
> Best,
> Hande
>
> --
> Hande Toffoli
> Department of Physics
> Office 439
> Middle East Technical University
> Ankara 06531, Turkey
> Tel : +90 312 210 3264
> http://www.physics.metu.edu.tr/~hande
> 
>
>
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org 
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>
>
>
> -- 
> Hai-Ping Lan
> Department of Electronics ,
> Peking University , Bejing, 100871
> lanhaiping at gmail.com , hplan at pku.edu.cn 
> 
> 
>
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>   

[Pw_forum] npwx in pwscf v.4.0

[Peter Winey]

Got it. Thanks a lot for the quick reply!

-Peter

On 8/13/08, Eyvaz Isaev  wrote:
>
> Dear Peter,
>
> nbnd now is printed as "number of Kohn-Sham states",
> as concerns npwx, it is worth looking at
> "Kohn-Sham Wavefunctions" right after k-points, where the firts number is
> npwx, the second one, again, is nbnd.
>
> 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
>
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[Pw_forum] IOTK library

[alan chen]

Dear PWSCF users,
  I have encountered this problem many times and I checked the archive
but I still did not get how to fix the problem. Some of my jobs are killed
by the following errors:


# FROM IOTK LIBRARY, VERSION 1.1.0development
# UNRECOVERABLE ERROR (ierr=1)
# ERROR IN: iotk_getline (iotk_scan.spp:812)
# CVS Revision: 1.7
#
iostat=-1
# ERROR IN: iotk_scan_tag (iotk_scan.spp:516)
# CVS Revision: 1.7
# ERROR IN: iotk_scan (iotk_scan.spp:710)
# CVS Revision: 1.7
# ERROR IN: iotk_scan_end (iotk_scan.spp:211)
# CVS Revision: 1.7
# foundl
# ERROR IN: iotk_close_read (iotk_files.spp:589)
# CVS Revision: 1.3


Paolo suggested a quick fix: change Q_REAL in Q_REAL_SPACE in
Modules/xml_io_base.f90 (thanks to Giovanni Bussi).
Does that mean: replace Q_REAL_SPACE by Q_REAL?  Could any one provide more
specific procedures to fix the bug?
Thank you very much.

Hanghui Chen
Department of Physics,
Yale University
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[Pw_forum] npwx in pwscf v.4.0

[Peter Winey]

Dear all,

I just noticed that in pwscf v4.0, some information, such as nbnd and npwx
etc,
are no longer printed out in the pw.x output file, even when I used
"verbosity= high".

I am particular interested in knowing "npwx". Is there a quick way of
getting it or
do I have to go back to version 3.2.x?

Thanks in advance!

-Peter


Peter Winey, Ph.D., DuPont
peterwiney at gmail.com

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[Pw_forum] Wavefunction format documentation for PWSCF version 3.0

[Steven Kirk]

Hello,

I have some old simulation results produced using PWSCF v3.0, 
specifically old input files, .wfc and .chdens files. I need to be able 
to extract the wavefunction information in order to calculate the Bohm 
quantum potential. Is there any documentation for the .wfc file format 
other than the source code itself? If so, where can I find it?

Regards,
Steve Kirk

-- 
Dr. Steven R. Kirk   
Dept. of Technology, Mathematics & Computer Science  (P)+46 520 223215
University West  (F)+46 520 223299
Trollhattan 461 86 SWEDEN http://beacon.webhop.org

[Pw_forum] Fermi energy in 'scf' and 'nscf'(XQ Wang)

[wangxinquan]

>>Dear Guoying
>>
>> scf:   k-mesh grids   10*10*10  (282kpoints in
>> *.scf.out file)
>>   nscf:   we give 121 kpoints along high symmetry direction
>> 
>>
>>In order to find the Fermi energy, the code performs an integration in
>>k-space and this integration is of course numerically performed over the
>>kpoints you provide. In the nscf run, you provide a highly heterogeneous
>>set of kpoints so the Fermi energy you get is not the same as the scf
>>solution where the BZ is sampled more evenly (and also more densely in your
>>case). As a result, you should trust the scf result.

Dear Guoying,

In my opinion, you should use the nscf results if you want to calculate the 
band
structure. According to the example 08 of espresso-4.0.1, the calculation 
of DOS for Ni follows three steps:1. pw.x (scf);2.pw.x(nscf);3.dos.x(dos). The 
calculation 
of nscf modifies the wavefunctions obtained by scf calculations. You will see
that the k-points were identified manually in scf while they were automatically 
selected in
nscf. So the Fermi energy used in band structure calculation should be the 
result from nscf.
I'm not sure that the above suggestions are absolutely right. It's just my 
limited experience.
 You'd better investigate the README file in the example 08 by yourself.
Hope this help.

Cheers,
XQ Wang

=
X.Q. Wang 
wangxinquan at tju.edu.cn
School of Chemical Engineering and Technology
Tianjin University
92 Weijin Road, Tianjin, P. R. China
tel:86-22-27890268, fax: 86-22-27892301
=
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[Pw_forum] Fermi energy in 'scf' and 'nscf'(XQ Wang)

[Hande Ustunel]

Dear Prasenjit,

> If the difference in Fermi energy is quite large, what I would suggest is to
> increase the no. of k-points in the nscf cal. & redo it.

The fact that Guoying's nscf calculation was conducted along high symmetry
points suggests that it was to be followed by a band structure run. In that
case, it is not necessary to try to obtain a "good" Fermi energy from the
nscf run other than convince oneself since this is not the point
here. Besides, I don't think increasing the number of kpoints along these
high symmetry directions would mean much because since you would still have
a severely heterogeneous sampling. It should just sufficient to just draw
the band structure from nscf along with the Fermi energy from the scf
calculation. But you would be absolutely right if what we were trying to do
here was to, say, increase resolution in a DOS plot.

On a separate note, I suggest that you try bands rather than nscf if you
are trying to draw a band structure since nscf worries about symmetries and
creates extra points whereas bands just does the ones you ask it to do.

Best,
Hande

-- 
Hande Toffoli
Department of Physics
Office 439
Middle East Technical University
Ankara 06531, Turkey
Tel : +90 312 210 3264
http://www.physics.metu.edu.tr/~hande

[Pw_forum] Fermi energy in 'scf' and 'nscf'

[Guoying Gao]

Dear Hande,

Thanks for your answer. I have got it.
Regards!

Guoying

[Pw_forum] npwx in pwscf v.4.0

[Eyvaz Isaev]

Dear Peter,

nbnd now is printed as "number of Kohn-Sham states",
as concerns npwx, it is worth looking at 
"Kohn-Sham Wavefunctions" right after k-points, where the firts number is npwx, 
the second one, again, is nbnd.  

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 Thu, 8/14/08, Peter Winey  wrote:

> From: Peter Winey 
> Subject: [Pw_forum] npwx in pwscf v.4.0
> To: pw_forum at pwscf.org
> Date: Thursday, August 14, 2008, 1:22 AM
> Dear all,
> 
> I just noticed that in pwscf v4.0, some information, such
> as nbnd and npwx
> etc,
> are no longer printed out in the pw.x output file, even
> when I used
> "verbosity= high".
> 
> I am particular interested in knowing "npwx". Is
> there a quick way of
> getting it or
> do I have to go back to version 3.2.x?
> 
> Thanks in advance!
> 
> -Peter
> 
> 
> Peter Winey, Ph.D., DuPont
> peterwiney at gmail.com
> 
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum


  

[Pw_forum] plot with gnuplot

[Lawrence Lee]

Dear Mansoureh,

A better way to put the graphs into WORD is to first convert the eps
file into png (or other format like jpg. Personally I prefer png for its
small file size and lossless compression). To do this, if you are
Windows user, Photoshop will work fine. If you use Linux, GIMP can also
perform this conversion easily. If you would like to use commands, you
may install Imagemagick. Then type, for example,

convert -density 300 input.eps output.png

300 is the width resolution in dpi. If you omit this, you turn out to
have a low resolution png like what you saw before.

On Wed, 2008-08-13 at 07:50 +0330, Mansoureh Pashangpour wrote:
> Dear all
> I am using gnuplot to plot DOS plots,but when I make its output as a
> postscript file and then use it to make its pdf and send it to
> word.doc ,its resolution decreases.Does anyone a good sugesstion to
> solve this problem? 
> good luck
> Mansoureh
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
-- 
S.H. Lee
M.Phil
Physics Division
The CUHK Graduate School

___
 ?x?? - Yahoo! Messenger
 
???]?W?o???W?r???f
  http://messenger.yahoo.com.hk 

[Pw_forum] vc-relax in the presence of finite electric field

[alan chen]

Dear PWSCF users,
  I have done a calculation of LaAlO3 recently, using 'vc-relax' with
the contraints that only z-direction is relaxed and x,y directions are
fixed, and in the presence of finite electric field (based on Berry Phase
method). The input file is attached at the end.
  However I am very confused with the results. The equilibrium lattice
constant in z direction is c=0.95*a (a is the lattice constant in x and y
direction).  The final ionic polarization is 72.03 a.u. and electronic
polarization is 4.50 a.u. Then I use the equilibrium unit cell (c=0.95*a)
and just 'relax' the atoms in the presence of the same electric field. I
obtain: ionic polarization is 75.13 a.u. and electronic polarization is 1.36
a.u. Even more confusing is that if I use the equilibrium unit cell
(c=0.95*a) and  put the atom in the ideal position (i.e. no ionic
polarization), the reference ionic polarization is 73.24 a.u.
  Shall I trust the 'vc-relax' calculation in the presence of finite
electric field?
  Thank you very much.

Input file reads:
&CONTROL
 calculation='vc-relax'
 wf_collect=.true.
 pseudo_dir = './psp'
 outdir='/scratch'
 wfcdir='/scratch'
 prefix='sLAO-vc'
 tprnfor = .true.
 tstress = .true.
 disk_io='low'
 verbosity='high'
 dt=80.D0
 lelfield=.true.
 gdir=3
 nppstr=16
 nberrycyc=1
/
&SYSTEM
 ibrav=  6
 celldm(1) = 7.27
 celldm(3) = 0.9506
 nat=  5
 ntyp= 3
 ecutwfc = 30.0
 ecutrho = 180.0
 occupations='fixed'
 nosym=.true.
/&ELECTRONS
 diagonalization='david'
 mixing_beta = 0.7D0
 diago_david_ndim = 4
 startingwfc='random'
 startingpot='atomic'
 efield=0.00348
 conv_thr = 1.0d-9
/
&IONS
 ion_dynamics = 'damp'
 phase_space = 'full'
 pot_extrapolation = 'second_order'
 wfc_extrapolation = 'second_order'
/
&CELL
 cell_dynamics = 'damp-w'
 cell_dofree = 'z'
/
ATOMIC_SPECIES
 La  138.91 057-La-ca-nsp-hanghui.uspp.format.UPF
 Al  26.98  013-Al-ca--hanghui.uspp.format.UPF
 O   16.00  008-O-ca--vgrp.uspp.format.UPF
ATOMIC_POSITIONS crystal
 La 0.00 0.00 0.00
 Al 0.50 0.50 0.50
 O  0.50 0.50 0.00
 O  0.00 0.50 0.50
 O  0.50 0.00 0.50
K_POINTS crystal
256
(The k points are omitted here)

Hanghui Chen
Department of Physics
Yale University
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[Pw_forum] Fermi energy in 'scf' and 'nscf'(XQ Wang)

[Prasenjit Ghosh]

Dear Wang,

In principle both the scf & nscf should give exactly the same value of Fermi
energy if your calculations are converged w.r.t. the k-point sampling
(since evaluation of Fermi energy involves numerical integration in
k-space). The fact that that the two procedures give different energies
suggest that the k-point mesh is not converged. Since these are numerical
integrations, the more the no of k-points the more accurate is the value of
the integral. Therefore for Guoying's case, the value of Fermi energy
obtained from scf is more accurate than that from nscf as suggested by
Hande.

If the difference in Fermi energy is quite large, what I would suggest is to
increase the no. of k-points in the nscf cal. & redo it.

With regards,

Prasenjit.

2008/8/13 wangxinquan 

>  >>Dear Guoying
> >>
> >> scf:   k-mesh grids   10*10*10  (282kpoints in
> >> *.scf.out file)
>
> >>   nscf:   we give 121 kpoints along high symmetry direction
> >>
> >>
> >>In order to find the Fermi energy, the code performs an integration in
> >>k-space and this integration is of course numerically performed over the
> >>kpoints you provide. In the nscf run, you provide a highly heterogeneous
> >>set of kpoints so the Fermi energy you get is not the same as the scf
>
> >>solution where the BZ is sampled more evenly (and also more densely in your
> >>case). As a result, you should trust the scf result.
>
> Dear Guoying,
>
> In my opinion, you should use the nscf results if you want to calculate
> the band
> structure. According to the example 08 of espresso-4.0.1, the calculation
> of DOS for Ni follows three steps:1. pw.x (scf);2.pw.x(nscf);3.dos.x(dos).
> The calculation
> of nscf modifies the wavefunctions obtained by scf calculations. You will
> see
> that the k-points were identified manually in scf while they were
> automatically selected in
> nscf. So the Fermi energy used in band structure calculation should be the
> result from nscf.
> I'm not sure that the above suggestions are absolutely right. It's just
> my limited experience.
>  You'd better investigate the README file in the example 08 by yourself.
> Hope this help.
>
> Cheers,
> XQ Wang
>
>
> =
>
> X.Q. Wang
>
> wangxinquan at tju.edu.cn
>
> School of Chemical Engineering and Technology
>
> Tianjin University
>
> 92 Weijin Road, Tianjin, P. R. China
>
> tel:86-22-27890268, fax: 86-22-27892301
>
> =
>
>
>
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>


-- 
PRASENJIT GHOSH,
POST-DOC,
ROOM NO: 265, MAIN BUILDING,
CM SECTION, ICTP,
STRADA COSTERIA 11,
TRIESTE, 34104,
ITALY
PHONE: +39 040 2240 369 (O)
+39 3807528672 (M)
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[Pw_forum] Fermi energy in 'scf' and 'nscf'

[Guoying Gao]

Dear PW users,

   I performed a electronic band structure calculation with
"m-p" smearing using Quantum-ESPRESSO code. At the end of 'scf and
'nscf' calculations, both gave Fermi energy. However, they are not the
same.

some parameters in the input file:

scf:   k-mesh grids   10*10*10  (282kpoints in
*.scf.out file)
  nscf:   we give 121 kpoints along high symmetry direction

 What I want to know is: why the two Fermi energy is
different,  if we want to plot energy band structure which Fermi
energy should we use, why?
 Any suggestions will be welcomed.

Best wishes!

Guoying

National Lab of Superhard Materials
Jilin Univ.
P.R.China

[Pw_forum] Fermi energy in 'scf' and 'nscf'

[Hande Ustunel]

Dear Guoying,

> scf:   k-mesh grids   10*10*10  (282kpoints in
> *.scf.out file)
>   nscf:   we give 121 kpoints along high symmetry direction
> 

In order to find the Fermi energy, the code performs an integration in
k-space and this integration is of course numerically performed over the
kpoints you provide. In the nscf run, you provide a highly heterogeneous
set of kpoints so the Fermi energy you get is not the same as the scf
solution where the BZ is sampled more evenly (and also more densely in your
case). As a result, you should trust the scf result.

Best,
Hande

-- 
Hande Toffoli
Department of Physics
Office 439
Middle East Technical University
Ankara 06531, Turkey
Tel : +90 312 210 3264
http://www.physics.metu.edu.tr/~hande

[Pw_forum] plot with gnuplot

[Mansoureh Pashangpour]

Dear all
I am using gnuplot to plot DOS plots,but when I make its output as a
postscript file and then use it to make its pdf and send it to word.doc ,its
resolution decreases.Does anyone a good sugesstion to solve this problem?
good luck
Mansoureh
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