[Pw_forum] Request for Pseudopotentials Si and H

[Shaptrishi Sharma]

Hi Quantum espresso users,

I need the  following pseudopotential file for my simulation  Si.vbc.UPF and
H.vbc.UPF . Howeevr I could not find them in PWScf, so can anybody suggest
me from where can I download these pseudopotentials. Please help me!!
Thanks

Shaptarishi.
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[Pw_forum] Calculation of spin polarisation from PWscf

[lan haiping]

Hi, Dimpy!
I think it is a  well repeated question if you pay more attention to
previous messages or userguide.
As described in $QE/Doc/INPUT_PW.html:
'
nspin INTEGER  *Default:* 1

nspin = 1 :  non-polarized calculation (default)

nspin = 2 :  spin-polarized calculation, LSDA
 (magnetization along z axis)

nspin = 4 :  spin-polarized calculation, noncollinear
 (magnetization in generic direction)
 DO NOT specify nspin in this case;
 specify "noncolin=.TRUE." instead



Hope it helps

P.S. Please provide your affiliation as it is the basic Netiquette of QE
community .

Regards

On Fri, Aug 14, 2009 at 5:43 PM, Dimpy Sharma wrote:

>
> Hi there,
>
> I want to know how do we perform calculation for spin polarisation in
> PWscf, as I have odd number of electrons in my system. However I have one
> more thing to ask, in my previous system as I already wrote charge is wrong
> apperedin the output, but in that system there are even number of electrons,
> so is their any other probable reason?
>
> Can anybody help?
>
> Dimpy
>
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>
>


-- 
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping at gmail.com, hplan at pku.edu.cn
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[Pw_forum] line crossing Valance bands (VB) & CB

[Paolo Giannozzi]

On Thursday 06 August 2009 18:31, dev sharma wrote:

>  I have successfully calculated the band structure of my system. It is also
> matching the results. But when I plot my band structure in ps format only
> one line from conduction band and valance band is showing fluctuations.
> Means one line ,in ps output, from conduction band has apparently come down
> to valance band and vice versa. And this fluctuation is  just  at the end
> of graph. (means i have given 41 k points in calculations= 'bands' and in
> only last 3 there is some fluctuations, the whole other graphs is smooth
> otherwsie). 

I am not sure I understand what you mean. One possibility is the following:
when one calculates bands, a few high-lying states may not be the correct 
ones because of the way iterative diagonalization works (it starts from
an initial guess). This is a rather normal behavior. The highest states in a
band calculation should be discarded.

Paolo
-- 
Paolo Giannozzi, Democritos and Udine University

[Pw_forum] PAW pseudo-potential for Al and Ni

[Nguyen Thanh Cuong]

Dear pwscf users,

Does anyone have generated  the paw pseudo-potentials for Al and Ni with ld1 
code? Would you share the ld1 input files?

Thank you in advance for your helps.

Best regards,

Nguyen Thanh Cuong
Phd student
School of Materials Science
Japan Advanced Institute of Science and Technology

[Pw_forum] matdyn error

[Paolo Giannozzi]

On Friday 14 August 2009 07:55, Bipul Rakshit wrote:

> I am doing Gamma point phonon analysis for LaMnO3,
>  after running matdyn.x i am getting the following, error.

you calculated phonons at q=0 only, so all you can and should
do is to run dynmat.x (not matdyn.x) to apply the acoustic sum
rule and to calculate lo-to splitting. 

Paolo
-- 
Paolo Giannozzi, Democritos and Udine University

[Pw_forum] Request for Pseudopotentials Si and H

[Manoj Srivastava]

Hey SaptariBshi, 
 You can find them in /pseudo directory under espresso, e.g. 
espresso-4.0.4/pseudo


-Manoj Srivastava
University of Florida 
Gainesville, FL

On Fri, 14 Aug 2009, Shaptrishi Sharma wrote:

> Hi Quantum espresso users,
> 
> I need the  following pseudopotential file for my simulation  Si.vbc.UPF and
> H.vbc.UPF . Howeevr I could not find them in PWScf, so can anybody suggest
> me from where can I download these pseudopotentials. Please help me!!
> Thanks
> 
> Shaptarishi.
> 

[Pw_forum] ban band number

[dev sharma]

Hi 2 All,

I was trying to calculate optical properties of my system using Epsilon.x.
After Scf, when i run espilon it gave error
 Performing eps calculation...

 
 from epsilon : error # 1
 ban band number
 

 stopping ..

Please help and guide me , what does at mean and what is the possible
solution. ???
Thanks in advance

Dev sharma,
University of Delhi,
India
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[Pw_forum] Trying to clarify the dipole correction (again!)

[Stefano de Gironcoli]

J. J. Ramsey wrote:
> - Original Message 
>
>   
>> From: Stefano de Gironcoli 
>> To: PWSCF Forum 
>> Sent: Thursday, August 13, 2009 11:59:14 AM
>> Subject: Re: [Pw_forum] Trying to clarify the dipole correction (again!)
>>
>> Dear J.J. Ramsey
>>
>>  at variance with what is defined in Bengtsson's paper the dipole 
>> potential is not discontinuous  in QE but is defined by periodically 
>> alternating an increasing slope (associate to the "physical" electric 
>> field present in the cell) and a  rapidly decreasing slope that should 
>> be located in a region of negligibly small charge density. This is done 
>> to avoid too sharp features in the calculation.
>> 
>
> In other words, the discontinuity in Bengtsson's paper, where the slope is 
> infinite, is replaced by a large but finite slope.
>   
yes
>>so if emaxpos = 0.45 and eopreg=0.1 the region where the correction 
>> is physically meaningful goes from -45% to +45% of the cell and the 
>> regression  region  (that should contains no charge density)  occupies 
>> the central 10% of the cell. This is a good setting if you center your 
>> slab around the origin.
>> 
>
> I gather you mean the case where the slab is near the bottom of the unit cell.
>   
or centered around the origin like in the the Al(001) surface of 
example03..
remember that we have periodic boundary conditions and the origin does 
not have any special meaning.

stefano

[Pw_forum] scf

[Huiqun Zhou]

Alvaro,

I think you need to test total energy or total magnetization against degauss,
the value of degauss should be small enough to make total energy converge.


Huiqun Zhou
@Earth Sciences, Nanjing University, China
  - Original Message - 
  From: ?lvaro Alves 
  To: PWSCF Forum 
  Sent: Friday, August 14, 2009 5:43 AM
  Subject: Re: [Pw_forum] scf


Hello. I am doing a scf calculation system and uses degauss = 0.003 and 
needed change it  for 0001. With this new value, the calculation does not 
converge. What may be happening?  

Regards, Alvaro

A. S. Santos

--- Em qui, 13/8/09, ?lvaro Alves  escreveu:


  De: ?lvaro Alves 
  Assunto: [Pw_forum] scf
  Para: "pw" 
  Data: Quinta-feira, 13 de Agosto de 2009, 17:30


Hello I am doing a scf calculation system and uses degauss = 
0.003 and needed change it paar 0001. With this new value, the calculation does 
not converge. What may be happening? 

Regards, Alvaro


   


--
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Celebridades - M?sica - Esportes

  -Anexo incorporado-


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[Pw_forum] ban band number

[Stefano de Gironcoli]

grep -e "ban band" */*.f90returns the following:

PP/epsilon.f90:  IF ( REAL(nbnd, DP)  <= nelec / 2.0_DP ) CALL 
errore('epsilon', 'ban band number', 1)

I guess that this means you specified a too small value for nbnd.
I also guess that "ban" is a mispelling for "bad"

stefano

dev sharma wrote:
> Hi 2 All,
>
> I was trying to calculate optical properties of my system using 
> Epsilon.x. After Scf, when i run espilon it gave error
>  Performing eps calculation...
>
>  
>  from epsilon : error # 1
>  ban band number
>  
>
>  stopping ..
>
> Please help and guide me , what does at mean and what is the possible 
> solution. ???
> Thanks in advance
>
> Dev sharma,
> University of Delhi,
> India
> 
>
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>   

[Pw_forum] matdyn error

[Bipul Rakshit]

Dear pwscf users,

I am doing Gamma point phonon analysis for LaMnO3, after running matdyn.x i
am getting the following, error.

Norm of the difference between old and new effective charges:
0.
Norm of the difference between old and new force-constants:
0.20461738165775616993
  0.833

 %%
 from frc_blk : error # 1
 wrong total_weight
 %%

 stopping ...
2

Since at gamma point i am getting some -ve freq. the sum rule i want to
apply. And to see the final frequencies after applying sum rule.

Kindly guide me and suggest for the possible reason for this error.
-- 
Dr. Bipul Rakshit
Research Associate,
S N Bose Centre for Basic Sciences,
Salt Lake,
Kolkata 700 098
India
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[Pw_forum] scf

[Stefano de Gironcoli]

dear Alvaro
 
  0.003 Ry is about 50 meV ... a very small value, and 0.001 is even 
smaller. this will require almost and infinity of  k-points in order  to 
obtain converged results... and such a small value may make scf 
convergence very difficult (unless very many k-points are used) because 
from one  iteration to the next the occupation of levels can suddenly 
change in a non-linear way making the mixing scheme ineffective...
are you sure you need such a small value of degauss ?

 stefano de Gironcoli - SISSA and DEMOCRITOS

?lvaro Alves wrote:
> Hello I am doing a scf calculation system and uses degauss = 0.003 and 
> needed change it paar 0001. With this new value, the calculation does 
> not converge. What may be happening?
>
> Regards, Alvaro
>
>
>
> 
> Veja quais s?o os assuntos do momento no Yahoo! + Buscados: Top 10 
> 
>  
> - Celebridades 
> 
>  
> - M?sica 
> 
>  
> - Esportes 
> 
>  
>
> 
>
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> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>   

[Pw_forum] Calculation of spin polarisation from PWscf

[Dimpy Sharma]

Hi there,

I want to know how do we perform calculation for spin polarisation in PWscf, as 
I have odd number of electrons in my system. However I have one more thing to 
ask, in my previous system as I already wrote charge is wrong apperedin the 
output, but in that system there are even number of electrons, so is their any 
other probable reason?

Can anybody help?

Dimpy
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[Pw_forum] Frequency and zero point energy calculations

[Gabriele Sclauzero]

Dear Lihui Ou,

oulihui666 wrote:
> Dear all,
> Recently, I have been performing calulation of frequency and zero 
> point energy of CO2 molecule. However, unfortunately, I have 
> obtained negative frequency. According to the manual, there are several 

>ibrav = 1,
>celldm(1) = 15.11781502,

This seems too small. You want to avoid spurious interactions between periodic 
replicas of 
the molecule.

>  nat = 3,
> ntyp = 2,
>  ecutwfc = 26 ,
>  ecutrho = 260 ,

These cut-offs may also be too small. C and O have 2p electrons which are hard 
to deal 
with PWs, even with US PPs.

>  occupations = 'smearing' ,
>  degauss = 0.02 ,

This is too large for a molecule, you can use much smaller values.

>  
> conv_thr = 1.D-12 ,

This requirement may be too strict. Anyway, if you don't have problems in 
convergence you 
can keep it as it is.

> (2) Performing scf calculations:
>  
>  calculation = 'scf' ,
> restart_mode = 'from_scratch' ,
>   outdir = '/home/olh/tmp/' ,
>   pseudo_dir = '/home/olh/pseudo/' ,
>   prefix = 'CO2' ,
>  /
>  
>ibrav = 1,
>celldm(1) = 15.11781502,
>  nat = 3,
> ntyp = 2,
>  ecutwfc = 26 ,
>  ecutrho = 260 ,
>  occupations = 'smearing' ,
>  degauss = 0.02 ,
> smearing = 'methfessel-paxton' ,
>nspin = 2 ,
>starting_magnetization(1) = 0.5,
>starting_magnetization(2) = 0.5,
>  /
>  
> conv_thr = 1.D-12 ,
>  mixing_beta = 0.4D0 ,
>  /
> ATOMIC_SPECIES
> C   12.01100  C.pbe-rrkjus.UPF
> O   15.99940  O.pbe-rrkjus.UPF
> ATOMIC_POSITIONS angstrom
> C4.0   4.0   4.00  0  0
> O5.172018724   4.0   4.00  0  0
> O2.827981276   4.0   4.00  0  0
> K_POINTS automatic
>   16 16 16  1 1 1

Maybe I don't understand what you want to calculate, but I don't see any need 
of a k-point 
sampling when computing an isolated molecule. Why don't you use gamma as in the 
relax 
calculation?


>  
> (3) Performing frequency calculation using PHONOS codes:
> phonons of CO2 at Gamma
>  
>   tr2_ph=1.0d-20,

This is very strict!

>   prefix='CO2',
>   epsil=.false.,
>   amass(1)=12.0110,
>   amass(2)=15.9994,
>   outdir='/home/olh/tmp/',
>   fildyn='CO2.dynG',
>  /
> 0.0 0.0 0.0



> Finally, I obtained the frequency of CO2 molecule, output file as follows:
> Convergence has been achieved
> Number of q in the star =1
> List of q in the star:
>  1   0.0   0.0   0.0
> Diagonalizing the dynamical matrix
> q = (0.0   0.0   0.0 )
> **
> omega( 1) =  -3.661345 [THz] =-122.130124 [cm-1]
> omega( 2) =  -3.661345 [THz] =-122.130124 [cm-1]
> omega( 3) =   3.659957 [THz] = 122.083850 [cm-1]
> omega( 4) =   7.879986 [THz] = 262.849774 [cm-1]
> omega( 5) =   7.879986 [THz] = 262.849774 [cm-1]
> omega( 6) =  19.746862 [THz] = 658.688787 [cm-1]
> omega( 7) =  19.746862 [THz] = 658.688787 [cm-1]
> omega( 8) =  38.945041 [THz] =1299.075383 [cm-1]
> omega( 9) =  70.000609 [THz] =2334.984491 [cm-1]
> **
>  Mode symmetry, D_4h(4/mmm) point group:
>  omega(  1 -  2) =   -122.1  [cm-1]   --> E_g  X_5  M_5   R
>  omega(  3 -  3) =122.1  [cm-1]   --> A_2u X_4' M_4'  I
>  omega(  4 -  5) =262.8  [cm-1]   --> E_u  X_5' M_5'  I
>  omega(  6 -  7) =658.7  [cm-1]   --> E_u  X_5' M_5'  I
>  omega(  8 -  8) =   1299.1  [cm-1]   --> A_1g X_1  M_1   R
>  omega(  9 -  9) =   2335.0  [cm-1]   --> A_2u X_4' M_4'  I
>  **
>  PHONON   : 1h48m CPU time,2h25m wall time
> ..
> There are still negative frequency in output file by increasing K_POINTS 
> and reducing tr2_ph, anyone who help me will be appreciated.

Increasing the number of k-points won't help you, obviously... the first three 
frequencies 
should be zero, since they are associated to translational modes of the 
barycenter of the 
molecule. They come out non-zero for the convergence issues you mentioned in 
your mail. 
You can enforce acoustic sum rules with the appropriate flags in the input (see 
Doc/INPUT_PH.txt). Anyway, I don't think you need a phonon calculation to 

[Pw_forum] matdyn error

[Mikiyas Tsegaye]

Dear Rakshit,

I'm just copy pasting from a previous answer in the forum to the same  
question: it might help, it might not.

Hello,
   Assuming that there are no problems of numerical inaccuracy or  
inadequate convergence
thresholds, negative frequencies at gamma point in a geometry-relaxed  
system usually mean that
(within the system and the calculation method used) there is some  
distortion (decreasing the
symmetry of the system) which leads to lower energy, i.e. you are at a  
saddle point in the energy
hypersurface. You must move some atom out of the initial symmetry and  
optimize geometry
again starting from that modified situation. If you can obtain the  
vector coordinates for the normal
mode of vibration corresponding to the negative frequency, a  
displacement of the involved atoms,
proportional to that normal mode, by e.g. a maximum of 0.2 angstrom  
will give to you a starting
displaced geometry closer to the true energy minimum. Sometimes you  
need to do this several
times if not all of the negative frequencies disappear after the first  
attempt.
If, after obtaining a new geometry with no negative frequencies at the  
gamma point, you still have
negative frequencies at other BZ points, this means that your system  
is unstable against some
atomic displacements that multiply some of the primitive cell vectors  
by e.g. 2 or 3, leading to a
supercell. Curing this situation may be more tedious.
Good luck,
Jose C. Conesa
Instituto de Catalisis y Petroleoquimica, CSIC
Campus de Cantoblanco
28049 Madrid  -  Spain
Phone Nr. 34-91-5854766
Fax Nr. 34-91-5854760

>
>
> Message: 3
> Date: Fri, 14 Aug 2009 11:25:23 +0530
> From: Bipul Rakshit 
> Subject: [Pw_forum] matdyn error
> To: PWSCF Forum 
> Message-ID:
>   <3a749910908132255x13311317j4eb55858c46affe0 at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Dear pwscf users,
>
> I am doing Gamma point phonon analysis for LaMnO3, after running  
> matdyn.x i
> am getting the following, error.
>
> Norm of the difference between old and new effective charges:
> 0.
> Norm of the difference between old and new force-constants:
> 0.20461738165775616993
>  0.833
>
> % 
> %
> from frc_blk : error # 1
> wrong total_weight
> % 
> %
>
> stopping ...
> 2
>
> Since at gamma point i am getting some -ve freq. the sum rule i want  
> to
> apply. And to see the final frequencies after applying sum rule.
>
> Kindly guide me and suggest for the possible reason for this error.
> -- 
> Dr. Bipul Rakshit
> Research Associate,
> S N Bose Centre for Basic Sciences,
> Salt Lake,
> Kolkata 700 098
> India
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[Pw_forum] scf

[Stefano Baroni]

On Aug 13, 2009, at 10:38 PM, spmmal wrote:

> Is there any general rule of setting parameters to make the SCF
> calculation  converge. Thanks.

experience, hard work, common sense
SB

---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /  
stefanobaroni (skype)

La morale est une logique de l'action comme la logique est une morale  
de la pens?e - Jean Piaget

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[Pw_forum] scf

[Stefano Baroni]

Alvaro:

> Hello I am doing a scf calculation system and uses degauss = 0.003

i.e. 40 mev

> and needed change it paar 0001.

i.e. 1.3 mev, very small indeed

> With this new value, the calculation does not converge. What may be  
> happening?

I can only imagine you are using Gaussian smearing for an isolated  
molecule with a degenerate HOMO. the degeneracy is split by the low  
summetry imposed by the supercell, and the electronic structure  
oscillates between the two (or more) states corresponding to each  
partner of the multiplet. when you use a decent gaussian smearing, the  
code makes an average among the degenerate states and it converges.  
when the smearing is instead indecently small, it does not ... As you  
see, from the poor information you are providing, I can only guess.  
Why don't you provide a few bits of imformation, rather than trusting  
our clairvoyance?

>  Regards, Alvaro

I understand that you think we can read your thoughts, but we  
cannot ... and, as you know, we would also like to know the identity  
of those we correspon to in this forum. In the future, please provide  
your complete identity, including your affiliation.

Thanks - Stefano

---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /  
stefanobaroni (skype)

La morale est une logique de l'action comme la logique est une morale  
de la pens?e - Jean Piaget

Please, if possible, don't  send me MS Word or PowerPoint attachments
Why? See:  http://www.gnu.org/philosophy/no-word-attachments.html

[Pw_forum] negative a2F(w)/w

[Ali Tavana]

I know my system is instable, but calculation for the stable systems takes 160 
days for each q point on a 8 core machine!! In the other hand some people have 
published a Nature article about the superconductive properties calculation of 
that instable system with your code. Any way, thank you for your answer.

> 
> As discussed, many times in this forum, as well as in many
> textbooks,? 
> negative squared ferquencies are a signal of a mechanical
> instability.? 
> Are you sure that you want to spend a lot of computer
> resources? 
> calculating the supercondictive properties of an instable
> (and, hence,? 
> non-existent unless very special conditions occur) system?
> SB
>