[Pw_forum] force in sawlike potential
Thank you! My QE version is 4.0.4. I will go for the newest version to have a look. On Tue, Apr 21, 2009 at 10:21 PM, Lorenzo Paulatto wrote: > In data 21 aprile 2009 alle ore 15:55:29, Aihua Zhang > ha scritto: > > I had expected the force exerted on nucleus by the field would > > cancel the force on ion due to change in electron charge density, so the > > total force should vanish since the system is neutral. I also varied the > > cutoff energy, but failed to see a convergence behavior as shown below. > > Could anyone give me a clue? Thank you! > > dear Aihua Zhang, > that part of the code has been "fixed" more than once recently, hence the > answer depends on the exact version of QE you are using. > > regards > > > -- > Creato con il rivoluzionario client e-mail di Opera: > http://www.opera.com/mail/ > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- -- Research Fellow, Dept. of Physics, National Univ. of Singapore 10 Kent Ridge Crescent, Singapore, 119260 Tel: +65 6516 7844 -- -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090421/d8e2ba53/attachment-0001.htm
[Pw_forum] force in sawlike potential
Dear all,
I comment out the line to impose total force = 0 in forces.f90, and perform
a calculation of one atom in sawlike potential. The input file is attached
below. I had expected the force exerted on nucleus by the field would
cancel the force on ion due to change in electron charge density, so the
total force should vanish since the system is neutral. I also varied the
cutoff energy, but failed to see a convergence behavior as shown below.
Could anyone give me a clue? Thank you!
Ecut(Ry) Total force(Ry/au)
300.002729
400.003052
500.003848
600.86
700.000962
800.000137
900.003208
100 0.001271
The input file:
-
calculation = 'scf'
restart_mode='from_scratch',
prefix='c',
tstress = .true.
tprnfor = .true.
pseudo_dir = '.',
outdir='/scratch/local'
tefield=.true.
/
ibrav= 0, nat= 1, ntyp= 1,
ecutwfc=100
edir=3
emaxpos=0.95
eopreg=0.1
eamp=0.001
/
diagonalization='cg'
mixing_mode = 'plain'
mixing_beta = 0.7
conv_thr = 1.0d-8
/
CELL_PARAMETERS
10 0 0
0 10 0
0 0 20
ATOMIC_SPECIES
C 1 C.pbe-rrkjus.UPF
ATOMIC_POSITIONS {bohr}
C 0.00 0.00 9.0
K_POINTS gamma
Best regards
zah
--
--
Research Fellow,
Dept. of Physics, National Univ. of Singapore
10 Kent Ridge Crescent, Singapore, 119260
Tel: +65 6516 7844
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[Pw_forum] reconstruction
Dear Ali You can start with (lateral) surface reconstruction of your bulk system. Afterwards I would try different supercells with different starting points, like number of atoms or "surface molecules". Don't forget to saturate dangling bonds (even there you can check different types). I think in Si NWs even a SiH3 group is outermost for some NWs After relaxing your structures you can check the most favorable ones by comparing energies (have a look at surface calculations for details). Good luck Marcel Mohr -- Institut f?r Festk?rperphysik TU Berlin On Tue, 21 Apr 2009, Prasenjit Ghosh wrote: > Dear Ali, > > It depends on the type of reconstruction the surface of the nanowire > undergoes.? May be if you tell a bit more about the type of reconstruction, I > can tell you more. > > Prasenjit. > > 2009/4/21 ali kazempoor > Dear Prasenjit > Thank you for your reply, but I mean what I do to see the surface > reconstruction at lateral nanowire surface. For simulation of a nanowire > in z direction we add vaccum around nanowire in x and y and for z we use > periodic boundary condition . So if we only suppose one unit > repetation in z , we can not observe the surface reconstruction . Therefor > for observing reconstruction , I think we have to make for > example twice unit repetation in z or more. > thanks > > --- On Tue, 4/21/09, Prasenjit Ghosh wrote: > > From: Prasenjit Ghosh > Subject: Re: [Pw_forum] reconstruction > To: "PWSCF Forum" > Date: Tuesday, April 21, 2009, 10:38 AM > > > Dear Ali, > > Usually when you speak of simulating a nanowire, because of the periodic > boundary conditions, you simulate an infinite one. If the > nanowire is aligned along Z axis, which seems to be your case,? then you have > periodicity along the Z-direction. Therefore you need > to? have enough vacuum along the x & y direction so that the periodic images > should not interact. > > Prasenjit. > > 2009/4/20 ali kazempoor > > Dear all > I want to study the fingerprint of reconstruction in nanowire facets. > How can ?I find that wheater I have surface > reconstruction or not? Should I make a bigger supercell in Z direction( > Z is the lenght of nanowire)? > thanks > Ali Kazempour.Isfahan University of Technology,Iran > > > > ___ > 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) > > -Inline Attachment Follows- > > ___ > Pw_forum mailing list > 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 > > > > > -- > 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) > >
[Pw_forum] reconstruction
Dear Ali, It depends on the type of reconstruction the surface of the nanowire undergoes. May be if you tell a bit more about the type of reconstruction, I can tell you more. Prasenjit. 2009/4/21 ali kazempoor > Dear Prasenjit > Thank you for your reply, but I mean what I do to see the surface > reconstruction at lateral nanowire surface. For simulation of a nanowire in > z direction we add vaccum around nanowire in x and y and for z we use > periodic boundary condition . So if we only suppose one unit repetation in z > , we can not observe the surface reconstruction . Therefor for observing > reconstruction , I think we have to make for example twice unit repetation > in z or more. > thanks > > --- On *Tue, 4/21/09, Prasenjit Ghosh * wrote: > > > From: Prasenjit Ghosh > Subject: Re: [Pw_forum] reconstruction > To: "PWSCF Forum" > Date: Tuesday, April 21, 2009, 10:38 AM > > > Dear Ali, > > Usually when you speak of simulating a nanowire, because of the periodic > boundary conditions, you simulate an infinite one. If the nanowire is > aligned along Z axis, which seems to be your case, then you have > periodicity along the Z-direction. Therefore you need to have enough vacuum > along the x & y direction so that the periodic images should not interact. > > Prasenjit. > > 2009/4/20 ali kazempoor yahoo.com<http://us.mc331.mail.yahoo.com/mc/compose?to=kazempoor2000 at > yahoo.com> > > > >> >> Dear all >> I want to study the fingerprint of reconstruction in nanowire facets. How >> can I find that wheater I have surface reconstruction or not? Should I make >> a bigger supercell in Z direction( Z is the lenght of nanowire)? >> thanks >> Ali Kazempour.Isfahan University of Technology,Iran >> >> >> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org<http://us.mc331.mail.yahoo.com/mc/compose?to=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) > > -Inline Attachment Follows- > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org<http://us.mc331.mail.yahoo.com/mc/compose?to=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 > > -- 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) -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090421/59bd23ee/attachment.htm
[Pw_forum] force in sawlike potential
In data 21 aprile 2009 alle ore 18:09:59, Aihua Zhang ha scritto: > Dear Paulatto, > > I compared the source codes under PW directory between 4.0.4 and 4.0.5. I > only found a minor relevant change in compute_dip.f90. I don't think this > change will affect the force. In fact, I was about to write there isn't any difference between 4.0.4 and 4.0.5, even though the sawtooth potential method is going through a redesign it won't be released very soon. What may be problematic is that your potential is that, in your case, emaxpos+eopreg is greater than 1. It should cause no harm, in theory, but I suspect the code may have some problem dealing with this case. What does it happen if you shift all your system half a basis vector down along the z direction? e.g. if you put the C atom in (0,0,0) and emaxpos=0.45, eopreg=0.10 regards -- Lorenzo Paulatto SISSA & DEMOCRITOS (Trieste) phone: +39 040 3787 511 skype: paulatz www: http://people.sissa.it/~paulatto/ *** save italian brains *** http://saveitalianbrains.wordpress.com/
[Pw_forum] force in sawlike potential
In data 21 aprile 2009 alle ore 15:55:29, Aihua Zhang ha scritto: > I had expected the force exerted on nucleus by the field would > cancel the force on ion due to change in electron charge density, so the > total force should vanish since the system is neutral. I also varied the > cutoff energy, but failed to see a convergence behavior as shown below. > Could anyone give me a clue? Thank you! dear Aihua Zhang, that part of the code has been "fixed" more than once recently, hence the answer depends on the exact version of QE you are using. regards -- Creato con il rivoluzionario client e-mail di Opera: http://www.opera.com/mail/
[Pw_forum] question for phonon calculation
> parameters used to generate.
Sorry, it should be "to generate a pseudopotential".
Bests,
Eyvaz.
--- On Tue, 4/21/09, Eyvaz Isaev wrote:
> From: Eyvaz Isaev
> Subject: Re: [Pw_forum] question for phonon calculation
> To: "PWSCF Forum"
> Date: Tuesday, April 21, 2009, 11:38 PM
> Hi,
>
> > But I got the minus value at the lowest three branch.
>
> > how to avoid the minus values
>
> Here you are incorrect, you got imaginary frequences.
>
> 5 years ago I did such kind calculations for MgB2 using my
> own PBE US pseudopotentials and met no problem. As far as
> know phonons are sensitive to parameters used to generate.
> Most likely, you can ignore these frequences, as applying
> ASR will correct them. As concerns how to apply ASR, just
> use matdyn.x in QE/PH or QE/bin (with keyword
> asr='crystal') file to generate phonon dispersion
> relations with correct acoustic modes at Gamma point. See
> example file /examples/example06.
>
> > tr2_ph=1.0d-25
> Looks extremly low. As 1.d-10 is default, the use of d-12
> or d-14 should be sufficient.
>
> 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 Tue, 4/21/09, ??
> wrote:
>
> > From: ??
> > Subject: [Pw_forum] question for phonon calculation
> > To: "pw forum"
> > Date: Tuesday, April 21, 2009, 10:23 PM
> > Dear All Users,
> >
> > I was going to calculating phonon frequency of MgB2 at
> > Gamma point.But I got
> > the minus value at the lowest three branch.
> >
> > q = (0.0 0.0 0.0
> )
> >
> >
> >
> **
> > omega( 1) = -1.333147 [THz] = -44.469304
> > [cm-1]
> > omega( 2) = -1.333147 [THz] = -44.469304
> > [cm-1]
> > omega( 3) = -1.003834 [THz] = -33.484515
> > [cm-1]
> > omega( 4) = 9.706117 [THz] = 323.763351
> > [cm-1]
> > omega( 5) = 9.706117 [THz] = 323.763351
> > [cm-1]
> > omega( 6) = 11.666010 [THz] = 389.138778
> > [cm-1]
> > omega( 7) = 15.807885 [THz] = 527.297796
> > [cm-1]
> > omega( 8) = 15.807885 [THz] = 527.297796
> > [cm-1]
> > omega( 9) = 20.623897 [THz] = 687.943739
> > [cm-1]
> >
> >
> **
> >
> > I had already relax the lattice.And below is my inputs
> for
> > scf and phonon
> > calculation.Any suggest and comments on how to avoid
> the
> > minus values was
> > appreciated.
> >
> > scf.in
> >
> > calculation = 'scf'
> > restart_mode='from_scratch'
> > prefix='MgB2',
> > pseudo_dir =
> > '//Quantum-Espresso/espresso-4.0.3/pseudo/',
> > outdir='/tmp/'
> > /
> >
> > ibrav=4,
> > celldm(1)=5.8398,
> > celldm(3)=1.1420,
> > nat=3,
> > ntyp=2,
> > ecutwfc = 45.0,
> > ecutrho = 450.0,
> > occupations= 'smearing',
> > degauss= 0.03,
> > smearing= 'cold',
> > /
> >
> > mixing_beta = 0.7
> > conv_thr = 1.0d-12
> > /
> > ATOMIC_SPECIES
> > Mg 24.3 Mg.pw91-np-van.UPF
> > B 10.8 B.pw91-n-van.UPF
> > ATOMIC_POSITIONS
> > Mg00 0
> > B 00.57735 0.571
> > B 0.5 0.28868 0.571
> > K_POINTS {automatic}
> > 32 32 32 0 0 0
> >
> > ph.in
> >
> > MgB2
> >
> > amass(1)= 24.3,
> > amass(2)= 10.8,
> > prefix='MgB2'
> > tr2_ph=1.0d-25,
> > alpha_mix(1)=0.5,
> > iverbosity=1,
> > outdir='//tmp/',
> > /
> > 0 0 0
> >
> > I also wonder how to apply 'asr' to my
> > calculation.I could not find any
> > option for ph.x.
> >
> > Have a nice day!
> >
> > Deng Pan
> > Nanjing University
> > ___
> > Pw_forum mailing list
> > 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
[Pw_forum] charged defect
Dear Ali > > I want to study O vacancy in TiO2 bulk There's a lot of people studying such an issue...! First, I suggest reading at least these papers: Phys. Rev. B vol. 73, pag. 125205 (2006). J. Chem. Phys. vol. 129, pag. 154113 (2008). Phys. Rev. B vol. 76, pag. 045217 (2007). Phys. Rev. B vol. 78, pag. 241201 (2008). Then, you will be aware that you need very large supercells and some kind of beyond-LDA (LDA+U or hybrid xc functionals) approximation in order to achieve a good description of point defects in TiO2. So, have a nice time... Dear Paolo > it's tricky, very tricky. May I suggest the following recent paper > by Alex Zunger: Phys. Rev. B78, 235104 (2008)? it is a general > paper on the problem of formation energies in charged defects. It's more than tricky... I'm starting in to think that TiO2 is not really a "regular" semiconductor. The paper by Zunger is of course an in-depth one, but native point defects in TiO2 seems to behave in a different way than, e.g., oxygen vacancies in ZnO (one of the topics of the Zunger's paper). This is not the suitable place for long debates, but I hope that such a scrap of an information can be useful to somebody. Cheers to everybody Giuseppe On Tuesday 21 April 2009 12:19:32 Paolo Giannozzi wrote: > On Apr 11, 2009, at 13:26 , ali kazempoor wrote: > > I want to study O vacancy in TiO2 bulk > > it's tricky, very tricky. May I suggest the following recent paper > by Alex Zunger: Phys. Rev. B78, 235104 (2008)? it is a general > paper on the problem of formation energies in charged defects. > > Paolo > --- > Paolo Giannozzi, Democritos and University of Udine, Italy > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- - Article premier - Les hommes naissent et demeurent libres et ?gaux en droits. Les distinctions sociales ne peuvent ?tre fond?es que sur l'utilit? commune - Article 2 - Le but de toute association politique est la conservation des droits naturels et imprescriptibles de l'homme. Ces droits sont la libert?, la propri?t?, la s?ret? et la r?sistance ? l'oppression. Giuseppe Mattioli CNR - ISTITUTO DI STRUTTURA DELLA MATERIA v. Salaria Km 29,300 - C.P. 10 I 00016 - Monterotondo Stazione (RM) Tel + 39 06 90672836 - Fax +39 06 90672316 E-mail: -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090421/7db70f5d/attachment.htm
[Pw_forum] charged defect
On Apr 11, 2009, at 13:26 , ali kazempoor wrote: > I want to study O vacancy in TiO2 bulk it's tricky, very tricky. May I suggest the following recent paper by Alex Zunger: Phys. Rev. B78, 235104 (2008)? it is a general paper on the problem of formation energies in charged defects. Paolo --- Paolo Giannozzi, Democritos and University of Udine, Italy
[Pw_forum] reconstruction
Dear Prasenjit Thank you for your reply, but I mean what I do to see the surface reconstruction at lateral nanowire surface. For simulation of a nanowire in z direction we add vaccum around nanowire in x and y and for z we use periodic boundary condition . So if we only suppose one unit repetation in z , we can not observe the surface reconstruction . Therefor for observing reconstruction , I think we have to make for example twice unit repetation in z or more. thanks --- On Tue, 4/21/09, Prasenjit Ghosh wrote: From: Prasenjit Ghosh <prasenjit@gmail.com> Subject: Re: [Pw_forum] reconstruction To: "PWSCF Forum" Date: Tuesday, April 21, 2009, 10:38 AM Dear Ali, Usually when you speak of simulating a nanowire, because of the periodic boundary conditions, you simulate an infinite one. If the nanowire is aligned along Z axis, which seems to be your case,? then you have periodicity along the Z-direction. Therefore you need to? have enough vacuum along the x & y direction so that the periodic images should not interact. Prasenjit. 2009/4/20 ali kazempoor Dear all I want to study the fingerprint of reconstruction in nanowire facets. How can ?I find that wheater I have surface reconstruction or not? Should I make a bigger supercell in Z direction( Z is the lenght of nanowire)? thanks Ali Kazempour.Isfahan University of Technology,Iran ___ 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) -Inline Attachment Follows- ___ Pw_forum mailing list Pw_forum at pwscf.org http://www.democritos.it/mailman/listinfo/pw_forum -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090421/cfbed207/attachment-0001.htm
[Pw_forum] Fw: reconstruction
--- On Mon, 4/20/09, ali kazempoor wrote: From: ali kazempoor <kazempoor2...@yahoo.com> Subject: reconstruction To: pw_forum at pwscf.org Date: Monday, April 20, 2009, 4:23 AM Dear all I want to study the fingerprint of reconstruction in nanowire facets. How can? I find that wheater I have surface reconstruction or not? Should I make a bigger supercell in Z direction( Z is the lenght of nanowire)? thanks Ali Kazempour.Isfahan University of Technology,Iran ? ? ? -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090421/48059560/attachment.htm
