[Pw_forum] something strange in rutile and anatase calculation

Axel Kohlmeyer akohlmey at cmm.chem.upenn.edu
Sun Aug 31 07:54:45 CEST 2008


On Sun, 31 Aug 2008, vega wrote:

VL> > A famous example is Li which PsP was removed from PWSCF website. I met the 
VL> > same problem with K and Cs using my own pseudopotentials.
VL> 
VL> Li PsP is still on the 
VL> website,http://www.quantum-espresso.org/pseudo/1.3/html/Li.html.

no. this was with reference to vanderbilt type 
lithium semi-core potentials.

they are actually back on www.pwscf.org due to popular demand.

those actually seem to work for phonons, provided one uses 
wavefunction cutoffs in the neighborhood of 200ry. getting 
a converged stress tensor is equally crazy, i needed 300ry
for a test system recently...

for the ultra-soft ones, phonons do not seem to work at all,
and there are some hints that this may be true for other 
"tricky" elements in combination with the vanderbilt scheme.

on the other hand, geometries and MD are working fine with
reasonable cutoffs (85-90ry for norm conserving and 30ry for 
ultrasoft with density cutoff ~300ry). this is what they were
created for and tested against.

as you can see, testing applicability of pseudopotentials
to the problem at hand is a good practice and should never
be underestimated. blindly trusting existing pseudopotentials
without knowing what they were used and parametrized for can
easily lead to the large errors...

cheers,
    axel.


VL> Name: Lithium
VL> Symbol: Li
VL> Atomic number: 3
VL> Atomic configuration: [He] 2s1
VL> Atomic mass: 6.914 (2)
VL> 
VL> Available pseudopotentials:
VL> 
VL> Li.pz-n-vbc.UPF   (details)
VL> 
VL> 	 Perdew-Zunger (LDA) exch-corr
VL> 	 nonlinear core-correction
VL> 	 Von Barth-Car (direct fit)
VL> 
VL> Li.pbe-n-van.UPF   (details)
VL> 
VL> 	 Perdew-Burke-Ernzerhof (PBE) exch-corr
VL> 	 nonlinear core-correction
VL> 	 Vanderbilt ultrasoft
VL> 
VL> Li.pw91-n-van.UPF   (details)
VL> 
VL> 	 Perdew-Wang 91 gradient-corrected functional
VL> 	 nonlinear core-correction
VL> 	 Vanderbilt ultrasoft
VL> 
VL> vega
VL> 
VL> =================================================================================
VL> Vega Lew (weijia liu)
VL> PH.D Candidate in Chemical Engineering
VL> State Key Laboratory of Materials-oriented Chemical Engineering
VL> College of Chemistry and Chemical Engineering
VL> Nanjing University of Technology, 210009, Nanjing, Jiangsu, China
VL> 
VL> --------------------------------------------------
VL> From: "Eyvaz Isaev" <eyvaz_isaev at yahoo.com>
VL> Sent: Sunday, August 31, 2008 4:19 AM
VL> To: "vega" <vegalew at hotmail.com>
VL> Subject: Re: [Pw_forum] something strange in rutile and anatase calculation
VL> 
VL> > --- On Sat, 8/30/08, vega <vegalew at hotmail.com> wrote:
VL> >
VL> >> thank you for replying
VL> >
VL> > Welcome.
VL> >
VL> >>
VL> >> >But as far as I know sometime PsPs (not for Ti, in
VL> >> general) fail with phonon calculations.
VL> >>
VL> >> Do you think there is a certain PsPs that could >calculate the lattice 
VL> >> parameters and bulk modulus correctly >but only fail with phonon 
VL> >> calculations.
VL> >
VL> 
VL> >
VL> >> If you find a certain PsPs fail with phonon calculations
VL> >> what will you do next? how to adjust it?
VL> >>
VL> > In this case you have to generate a new PsP, if you like to deal with 
VL> > phonons. Otherwise, use what you have and what you prefer.
VL> >
VL> > Bests,
VL> > Eyvaz.
VL> > P.S. This is not a problem of the QE code. Several times I heard complains 
VL> > about PAW potentials for VASP.
VL> >
VL> >> vega
VL> >>
VL> >>
VL> >> =================================================================================
VL> >> Vega Lew (weijia liu)
VL> >> PH.D Candidate in Chemical Engineering
VL> >> State Key Laboratory of Materials-oriented Chemical
VL> >> Engineering
VL> >> College of Chemistry and Chemical Engineering
VL> >> Nanjing University of Technology, 210009, Nanjing, Jiangsu,
VL> >> China
VL> >>
VL> >> --------------------------------------------------
VL> >> From: "Eyvaz Isaev" <eyvaz_isaev at yahoo.com>
VL> >> Sent: Sunday, August 31, 2008 12:15 AM
VL> >> To: "vega" <vegalew at hotmail.com>
VL> >> Subject: Re: [Pw_forum] something strange in rutile and
VL> >> anatase calculation
VL> >>
VL> >> > Dear Vega,
VL> >> >
VL> >> > --- On Sat, 8/30/08, vega <vegalew at hotmail.com>
VL> >> wrote:
VL> >> >
VL> >> >> > I have read the paper and have 2 comments.
VL> >> >>
VL> >> >> I used to think the paper was written by you. Why
VL> >> > did you need to read
VL> >> >> it again?
VL> >> >
VL> >> > As I replied to Willy Kohn's mail, I meant reading
VL> >> the paper from
VL> >> > Jpn.J.Appl.Phys. Lett., he recommended, but not my own
VL> >> paper from PNAS.
VL> >> > So, there will be no confusing.  All what I said
VL> >> concerned only the paper
VL> >> > and PsPs used in JpnJApplPhys.
VL> >> >
VL> >> > If you have done lots of calculations with the Ti
VL> >> pseudopotential you used
VL> >> > and got reliable results, well, it looks like to be
VL> >> transferable. The
VL> >> > transferability means that you can put a bare ionic
VL> >> atom (with its PsP)
VL> >> > into different environment, but its scattering
VL> >> properties should be the
VL> >> > same as for a real atom.
VL> >> > A transferable PsP for a given atom (say Ti) should
VL> >> work in most cases (as
VL> >> > in your case, if you got results comparable with
VL> >> experiments and
VL> >> > independent methods). The way you supposed (lattice
VL> >> parameters and bulk
VL> >> > modulus for known phases and compounds) is correct to
VL> >> check a PsP
VL> >> > transferability. But as far as I know sometime PsPs
VL> >> (not for Ti, in
VL> >> > general) fail with phonon calculations.
VL> >> >
VL> >> > As references you cited support your calculations you
VL> >> can belive your own
VL> >> > results.
VL> >> >
VL> >> > Hopefully I replied briefly all questions you posted
VL> >> in this mail.
VL> >> >
VL> >> > Bests,
VL> >> > Eyvaz.
VL> >> >
VL> >> >
VL> >> >> > 2. They used only LDA, but not GGA. As it is
VL> >> well
VL> >> >> known (hopefully I am
VL> >> >> > not wrong here) LDA fails for the ground
VL> >> state of Fe.
VL> >> >> In contrast to this,
VL> >> >> > GGA does a good job for Fe.
VL> >> >>
VL> >> >> But I found the sentence like this, 'The
VL> >> generalized
VL> >> >> gradient approximation
VL> >> >> in the Perdew-
VL> >> >> Burke-Ernzerhof parametrization was chosen to
VL> >> treat the
VL> >> >> exchange-correlation
VL> >> >> effects.' in the Methods section. I was rather
VL> >> >> confused.
VL> >> >>
VL> >> >> > So, it will be very good if Vega can
VL> >> calculate the
VL> >> >> total energies for the
VL> >> >> > rutile and anatase phases in odrer to study
VL> >> whether
VL> >> >> their energy position
VL> >> >> > is dependent on the choice of
VL> >> exchange-correlation
VL> >> >> functional.
VL> >> >>
VL> >> >> I used to do a little test against this. The
VL> >> results
VL> >> >> suggested that the GGA
VL> >> >> overestimate the lattice parameters a little with
VL> >> 1% and
VL> >> >> LDA underestimate
VL> >> >> the lattice parameters for both case. I didn't
VL> >> pay a
VL> >> >> lot attentions on
VL> >> >> energy position calculated by LDA. I'll check
VL> >> it as
VL> >> >> soon as possible. But to
VL> >> >> my best knowledge, there were many reports
VL> >> suggested that
VL> >> >> the calculated
VL> >> >> anatase stability was better than rutile. For
VL> >> example, J.
VL> >> >> Chem. Phys. 126,
VL> >> >> 154703 (2007) said 'No matter which
VL> >> Hamiltonian or
VL> >> >> method is used, the
VL> >> >> results on relative stability of both phases
VL> >> suggest that
VL> >> >> the anatase is
VL> >> >> more stable than the rutile phase of TiO2.'.
VL> >> Same
VL> >> >> conclusion also was
VL> >> >> mentioned in Phys. Rev. B 2002, 65 (22) and Phys.
VL> >> Rev. B
VL> >> >> 2007, 76 et al.
VL> >> >>
VL> >> >> > It might also be that there is a
VL> >> transferability
VL> >> >> problem for these PsPs (I
VL> >> >> > can not prove this, just suggestion).
VL> >> >>
VL> >> >> Because I'm a beginner for QE. I though
VL> >> >> pseudopotentials is quite
VL> >> >> transferable and we could use the same
VL> >> pseudopotentials for
VL> >> >> any mater
VL> >> >> containing the same kind of element. For instance,
VL> >> we could
VL> >> >> use the same
VL> >> >> pseudopotentials for hcp Ti, TiN, rutile,
VL> >> brookite, anatase
VL> >> >> and other
VL> >> >> polymorphs under high pressure, such as
VL> >> >> Fluorite,Baddeleyite et al. But now,
VL> >> >> I think I'm probably wrong. Could you tell me
VL> >> the
VL> >> >> difference between the Ti
VL> >> >> pseudopotentials for hcp-Ti and TiN or many
VL> >> polymorphs of
VL> >> >> TiO2? And I also
VL> >> >> wonder how to judge whether the pseudopotentials
VL> >> is
VL> >> >> suitable for certain
VL> >> >> calculation? to calculate the lattice parameters
VL> >> and
VL> >> >> compare the results
VL> >> >> with the experimental data? Is that enough?
VL> >> >>
VL> >> >> > It is my pleasure that they also mentioned
VL> >> that
VL> >> >> including of phonon
VL> >> >> > contribution might be important.
VL> >> >> I would like to calculate the phonon contribution.
VL> >> But I
VL> >> >> have few knowledge
VL> >> >> about it. I'll learn to do that if necessary.
VL> >> >>
VL> >> >> vega
VL> >> >>
VL> >> >>
VL> >> >>
VL> >> =================================================================================
VL> >> >> Vega Lew (weijia liu)
VL> >> >> PH.D Candidate in Chemical Engineering
VL> >> >> State Key Laboratory of Materials-oriented
VL> >> Chemical
VL> >> >> Engineering
VL> >> >> College of Chemistry and Chemical Engineering
VL> >> >> Nanjing University of Technology, 210009, Nanjing,
VL> >> Jiangsu,
VL> >> >> China
VL> >> >>
VL> >> >> --------------------------------------------------
VL> >> >> From: "Eyvaz Isaev"
VL> >> <eyvaz_isaev at yahoo.com>
VL> >> >> Sent: Saturday, August 30, 2008 7:14 AM
VL> >> >> To: "PWSCF Forum"
VL> >> <pw_forum at pwscf.org>
VL> >> >> Subject: Re: [Pw_forum] something strange in
VL> >> rutile and
VL> >> >> anatase calculation
VL> >> >>
VL> >> >> > Dear Wei,
VL> >> >> >
VL> >> >> > Thanks a lot for bringing the paper to our
VL> >> attention.
VL> >> >> >
VL> >> >> > I have read the paper and have 2 comments.
VL> >> >> >
VL> >> >> > 1. They used only norm-conserving
VL> >> pseudopotentials
VL> >> >> constructed by means of
VL> >> >> > different methods.
VL> >> >> >
VL> >> >> > 2. They used only LDA, but not GGA. As it is
VL> >> well
VL> >> >> known (hopefully I am
VL> >> >> > not wrong here) LDA fails for the ground
VL> >> state of Fe.
VL> >> >> In contrast to this,
VL> >> >> > GGA does a good job for Fe.
VL> >> >> >
VL> >> >> > So, it will be very good if Vega can
VL> >> calculate the
VL> >> >> total energies for the
VL> >> >> > rutile and anatase phases in odrer to study
VL> >> whether
VL> >> >> their energy position
VL> >> >> > is dependent on the choice of
VL> >> exchange-correlation
VL> >> >> functional.
VL> >> >> >
VL> >> >> > It might also be that there is a
VL> >> transferability
VL> >> >> problem for these PsPs (I
VL> >> >> > can not prove this, just suggestion).
VL> >> >> >
VL> >> >> > It is my pleasure that they also mentioned
VL> >> that
VL> >> >> including of phonon
VL> >> >> > contribution might be important.
VL> >> >> >
VL> >> >> > Bests,
VL> >> >> > Eyvaz.
VL> >> >> >
VL> >> >> >
VL> >> >>
VL> >> -------------------------------------------------------------------
VL> >> >> > Prof. Eyvaz Isaev,
VL> >> >> > Theoretical Physics Department, Moscow State
VL> >> Institute
VL> >> >> of Steel & Alloys,
VL> >> >> > Russia,
VL> >> >> > Department of Physics, Chemistry, and Biology
VL> >> (IFM),
VL> >> >> Linkoping University,
VL> >> >> > Sweden
VL> >> >> > Condensed Matter Theory Group, Uppsala
VL> >> University,
VL> >> >> Sweden
VL> >> >> > Eyvaz.Isaev at fysik.uu.se, isaev at ifm.liu.se,
VL> >> >> eyvaz_isaev at yahoo.com
VL> >> >> >
VL> >> >> >
VL> >> >> > --- On Fri, 8/29/08, willy kohn
VL> >> >> <willykohn at gmail.com> wrote:
VL> >> >> >
VL> >> >> >> From: willy kohn
VL> >> <willykohn at gmail.com>
VL> >> >> >> Subject: Re: [Pw_forum] something strange
VL> >> in
VL> >> >> rutile and anatase
VL> >> >> >> calculation
VL> >> >> >> To: "PWSCF Forum"
VL> >> >> <pw_forum at pwscf.org>
VL> >> >> >> Date: Friday, August 29, 2008, 10:02 PM
VL> >> >> >> Hi, Vega:
VL> >> >> >>
VL> >> >> >> A recent result (Jpn. J. Appl. Phys. 39
VL> >> (2000)
VL> >> >> L847) showed
VL> >> >> >> that different
VL> >> >> >> pseudopotential leaded to different
VL> >> conclusions.
VL> >> >> >>
VL> >> >> >> Best,
VL> >> >> >>
VL> >> >> >> Wei
VL> >> >> >>
VL> >> >> >> On Thu, Aug 28, 2008 at 4:28 AM, vega
VL> >> >> >> <vegalew at hotmail.com> wrote:
VL> >> >> >>
VL> >> >> >> >  Dear all,
VL> >> >> >> >
VL> >> >> >> > It is known that the rutile is more
VL> >> stable
VL> >> >> than
VL> >> >> >> anatase in thermodynamics.
VL> >> >> >> > Surprisingly, when I did the
VL> >> vc-relax
VL> >> >> calculation by
VL> >> >> >> QE, I found
VL> >> >> >> > the calculated energy of anatase
VL> >> lower than
VL> >> >> rutile.
VL> >> >> >> Both vc-relax
VL> >> >> >> > calculation for rutile and anatase
VL> >> onverged
VL> >> >> in 6 scf
VL> >> >> >> cycles and 3 bfgs
VL> >> >> >> > steps, giving the final enthalpy =
VL> >> >> -362.7585836890 Ry
VL> >> >> >> for rutile and
VL> >> >> >> > -725.5447425835 Ry for antase. So
VL> >> the average
VL> >> >> energy
VL> >> >> >> of [TiO2] unit
VL> >> >> >> > is -181.3792918445 Ry for rutile and
VL> >> >> -181.386185645875
VL> >> >> >> Ry for anatase. It
VL> >> >> >> > looks like anatase is more stable
VL> >> than
VL> >> >> rutile. Do you
VL> >> >> >> think it was quite
VL> >> >> >> > strange?
VL> >> >> >> >
VL> >> >> >> > To make the calculation both for
VL> >> anatase and
VL> >> >> rutile
VL> >> >> >> comparable, I used the
VL> >> >> >> > same ecutwfc=40 Ry and ecutwfc=400
VL> >> Ry, and a
VL> >> >> quite
VL> >> >> >> dense k-point mesh for
VL> >> >> >> > both case, 4x4x7 for rutile and
VL> >> 5x5x2 for
VL> >> >> anatase.
VL> >> >> >> >
VL> >> >> >> > for better understanding in my
VL> >> calculation,
VL> >> >> please
VL> >> >> >> read the input file
VL> >> >> >> > below,
VL> >> >> >> > for anatase case,
VL> >> >> >> > &CONTROL
VL> >> >> >> >                        title =
VL> >> 'Anatase
VL> >> >> >> lattice' ,
VL> >> >> >> >                  calculation =
VL> >> >> 'vc-relax' ,
VL> >> >> >> >                 restart_mode =
VL> >> >> 'from_scratch'
VL> >> >> >> ,
VL> >> >> >> >                       outdir =
VL> >> >> >> >
VL> >> >> >>
VL> >> >>
VL> >> '/home/hjfeng/vega/TiO2/Anatase/lattice/vctest/tmp/'
VL> >> >> >> ,
VL> >> >> >> >                       wfcdir =
VL> >> >> '/tmp/' ,
VL> >> >> >> >                   pseudo_dir =
VL> >> >> >>
VL> >> '/home/hjfeng/vega/espresso-4.0/pseudo/' ,
VL> >> >> >> >                       prefix =
VL> >> 'Anatase
VL> >> >> >> lattice' ,
VL> >> >> >> >                      disk_io =
VL> >> 'none'
VL> >> >> ,
VL> >> >> >> >                        nstep = 1000
VL> >> ,
VL> >> >> >> >  /
VL> >> >> >> >  &SYSTEM
VL> >> >> >> >                        ibrav = 6,
VL> >> >> >> >                    celldm(1) =
VL> >> 7.1356,
VL> >> >> >> >                    celldm(3) =
VL> >> 2.5122,
VL> >> >> >> >                          nat = 12,
VL> >> >> >> >                         ntyp = 2,
VL> >> >> >> >                      ecutwfc = 40 ,
VL> >> >> >> >                      ecutrho = 400 ,
VL> >> >> >> >  /
VL> >> >> >> >  &ELECTRONS
VL> >> >> >> >
VL> >> >> >> >  /
VL> >> >> >> >  &IONS
VL> >> >> >> >                 ion_dynamics =
VL> >> 'bfgs'
VL> >> >> ,
VL> >> >> >> >  /
VL> >> >> >> >  &CELL
VL> >> >> >> >                cell_dynamics =
VL> >> 'bfgs'
VL> >> >> ,
VL> >> >> >> >  /
VL> >> >> >> > ATOMIC_SPECIES
VL> >> >> >> >    Ti   47.86700
VL> >> Ti.pw91-sp-van_ak.UPF
VL> >> >> >> >     O   15.99940  O.pw91-van_ak.UPF
VL> >> >> >> > ATOMIC_POSITIONS crystal
VL> >> >> >> >    Ti      0.000000000
VL> >> 0.000000000
VL> >> >> 0.000000000
VL> >> >> >> >    Ti      0.500000000
VL> >> 0.500000000
VL> >> >> 0.500000000
VL> >> >> >> >    Ti      0.000000000
VL> >> 0.500000000
VL> >> >> 0.250000000
VL> >> >> >> >    Ti      0.500000000
VL> >> 0.000000000
VL> >> >> 0.750000000
VL> >> >> >> >     O      0.000000000
VL> >> 0.500000000
VL> >> >> 0.042000000
VL> >> >> >> >     O      0.000000000
VL> >> 0.000000000
VL> >> >> 0.208000000
VL> >> >> >> >     O      0.500000000
VL> >> 0.500000000
VL> >> >> 0.292000000
VL> >> >> >> >     O      0.000000000
VL> >> 0.500000000
VL> >> >> 0.458000000
VL> >> >> >> >     O      0.500000000
VL> >> 0.000000000
VL> >> >> 0.542000000
VL> >> >> >> >     O      0.500000000
VL> >> 0.500000000
VL> >> >> 0.708000000
VL> >> >> >> >     O      0.000000000
VL> >> 0.000000000
VL> >> >> 0.792000000
VL> >> >> >> >     O      0.500000000
VL> >> 1.000000000
VL> >> >> 0.958000000
VL> >> >> >> > K_POINTS automatic
VL> >> >> >> >   5 5 2   1 1 1
VL> >> >> >> >
VL> >> >> >> > for rutile case,
VL> >> >> >> >
VL> >> >> >> >     &CONTROL
VL> >> >> >> >                        title =
VL> >> Rutile_lattice
VL> >> >> ,
VL> >> >> >> >                  calculation =
VL> >> >> 'vc-relax' ,
VL> >> >> >> >                 restart_mode =
VL> >> >> 'from_scratch'
VL> >> >> >> ,
VL> >> >> >> >                       outdir =
VL> >> >> >> >
VL> >> >>
VL> >> '/home/vega32/TiO2/rutile/lattice/vcrelax/tmp'
VL> >> >> >> ,
VL> >> >> >> >                       wfcdir =
VL> >> >> '/tmp/' ,
VL> >> >> >> >                   pseudo_dir =
VL> >> >> >>
VL> >> '/home/vega32/espresso-4.0.1/pseudo/' ,
VL> >> >> >> >                       prefix =
VL> >> 'Anatase
VL> >> >> >> lattice' ,
VL> >> >> >> >                      disk_io =
VL> >> 'none'
VL> >> >> ,
VL> >> >> >> >                        nstep = 1000
VL> >> ,
VL> >> >> >> >  /
VL> >> >> >> >  &SYSTEM
VL> >> >> >> >                        ibrav = 6,
VL> >> >> >> >                    celldm(1) =
VL> >> 8.6814,
VL> >> >> >> >                    celldm(3) =
VL> >> 0.6441,
VL> >> >> >> >                          nat = 6,
VL> >> >> >> >                         ntyp = 2,
VL> >> >> >> >                      ecutwfc = 40 ,
VL> >> >> >> >                      ecutrho = 400 ,
VL> >> >> >> >  /
VL> >> >> >> >  &ELECTRONS
VL> >> >> >> >
VL> >> >> >> >  /
VL> >> >> >> >  &IONS
VL> >> >> >> >                 ion_dynamics =
VL> >> 'bfgs'
VL> >> >> ,
VL> >> >> >> >  /
VL> >> >> >> >  &CELL
VL> >> >> >> >                cell_dynamics =
VL> >> 'bfgs'
VL> >> >> ,
VL> >> >> >> >  /
VL> >> >> >> > ATOMIC_SPECIES
VL> >> >> >> >     O   15.99940  O.pw91-van_ak.UPF
VL> >> >> >> >    Ti   47.90000
VL> >> Ti.pw91-sp-van_ak.UPF
VL> >> >> >> > ATOMIC_POSITIONS crystal
VL> >> >> >> >     O      0.304800000
VL> >> 0.304800000
VL> >> >> 0.000000000
VL> >> >> >> >     O      0.695200000
VL> >> 0.695200000
VL> >> >> 0.000000000
VL> >> >> >> >     O      0.195200000
VL> >> 0.804800000
VL> >> >> 0.500000000
VL> >> >> >> >     O      0.804800000
VL> >> 0.195200000
VL> >> >> 0.500000000
VL> >> >> >> >    Ti      0.500000000
VL> >> 0.500000000
VL> >> >> 0.500000000
VL> >> >> >> >    Ti      0.000000000
VL> >> 0.000000000
VL> >> >> 0.000000000
VL> >> >> >> > K_POINTS automatic
VL> >> >> >> >   4 4 7   1 1 1
VL> >> >> >> >
VL> >> >> >> > vega
VL> >> >> >> >
VL> >> >> >> >
VL> >> >> >>
VL> >> >>
VL> >> ==============================================================
VL> >> >> >> > Vega Lew ( weijia liu)
VL> >> >> >> > PH.D Candidate in Chemical
VL> >> Engineering
VL> >> >> >> > State Key Laboratory of
VL> >> Materials-oriented
VL> >> >> Chemical
VL> >> >> >> Engineering
VL> >> >> >> > College of Chemistry and Chemical
VL> >> Engineering
VL> >> >> >> > Nanjing University of Technology,
VL> >> 210009,
VL> >> >> Nanjing,
VL> >> >> >> Jiangsu, China
VL> >> >> >> >
VL> >> >> >> >
VL> >> >> _______________________________________________
VL> >> >> >> > Pw_forum mailing list
VL> >> >> >> > Pw_forum at pwscf.org
VL> >> >> >> >
VL> >> >> http://www.democritos.it/mailman/listinfo/pw_forum
VL> >> >> >> >
VL> >> >> >> >
VL> >> >> >>
VL> >> _______________________________________________
VL> >> >> >> Pw_forum mailing list
VL> >> >> >> Pw_forum at pwscf.org
VL> >> >> >>
VL> >> http://www.democritos.it/mailman/listinfo/pw_forum
VL> >> >> >
VL> >> >> >
VL> >> >> >
VL> >> >> >
VL> >> _______________________________________________
VL> >> >> > Pw_forum mailing list
VL> >> >> > Pw_forum at pwscf.org
VL> >> >> >
VL> >> http://www.democritos.it/mailman/listinfo/pw_forum
VL> >> >> >
VL> >> >
VL> >> >
VL> >> >
VL> >> >
VL> >
VL> >
VL> >
VL> > 
VL> _______________________________________________
VL> Pw_forum mailing list
VL> Pw_forum at pwscf.org
VL> http://www.democritos.it/mailman/listinfo/pw_forum
VL> 

-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
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