[Pw_forum] CuO, LDA+U, Pseudopots, etc.

[Paul M. Grant]

To All responding to my initial thread:

I'm amazed and encouraged by the response of the community to my problem.  I
will be trying your suggestions...e.g., a "rich man's" Wannier projection.
Of course, this trapping into a "metastable state" is typical of many highly
nonlinear systems of any type...such as the many body nonlinear
Navier-Stokes equations, sometimes referred to as the "weather."

Someone pointed out the importance of covalency in the Cu-O double bond, and
I'm not sure how to accommodate this in PWscf (in the simple Hubbard
Hamiltonian, you just futz around with U and t in a Monte Carlo
simulation...in 1 or 2 dimensions).  As I mentioned in my original posting,
there may be a profound issue here that DFT LDA+U may find difficult to
address...it's probably the origin of HTSC.  There is a polemic published
back in 1989 by Phil Anderson to the effect that pseudopotential theory may
not apply to divalent Cu-O bonds.

Nonetheless, I would still like to find a way to get a Hubbard Gap in
divalent CuO from a PW/PP starting point.  I'm old enough to remember this
was once quite a task for NiO.

Paul M. Grant, PhD
Principal, W2AGZ Technologies
Visiting Scholar, Applied Physics, Stanford University
EPRI Science Fellow (Retired)
IBM Research Staff Member Emeritus
w2agz at pacbell.net
http://www.w2agz.com
?
?


-Original Message-
From: pw_forum-bounces at pwscf.org [mailto:pw_forum-boun...@pwscf.org] On
Behalf Of Agostino Migliore
Sent: Thursday, December 13, 2007 10:01 PM
To: PWSCF Forum
Subject: Re: [Pw_forum] CuO, LDA+U, Pseudopots, etc.

Yes, I know. By saying "convergence problem" I just meant, in this
specific case, that the scf calculation does not reach the right minimum
(i.e., the lowest one), but get trapped into some another (local) minimum.
As to your second point, I will send you a further email in a short time.
Thank you

Agostino
>
>
> Dear Agostino,
>
> if the calculation did converge to a local minimum, it means that the
> system has more than one minimum, not that there is a convergence
> problem (of course, the convergence strategy you choose will affect
> the minimum in which you fall).
>
> It would be very interesting to know more (when you have time) about
> these minima - e.g. what were the projections of the minority spin
> in the two cases.
>
> Thanks !
>
>   nicola

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[Pw_forum] CuO, LDA+U, Pseudopots, etc.

[Nicola Marzari]

Agostino Migliore wrote:
> Hello
> 
> Also independently of this specific problem, I use the occasion to say
> that sometimes, with finite U, the code gets trapped in local minima for
> some values of the "mixing_beta" parameter.

Did you characterize the local minimum, by any chance ? The system
is fairly simple (on one side, 5 d electrons, say all up, and
on the other side, 6 d electrons). Do you have a sense if the
additional minimum is due to some long range ferro vs. antiferro
coupling between the two ions (i.e. 5 up on one side, and 5 up and
1 down, vs 5 up, 5 down and 1 up), or if the minorit spin on the ferric
ion splits in two or three orbtials with fractional occupations ?


nicola

-- 
-
Prof Nicola Marzari   Department of Materials Science and Engineering
13-5066   MIT   77 Massachusetts Avenue   Cambridge MA 02139-4307 USA
tel 617.4522758 fax 2586534 marzari at mit.edu http://quasiamore.mit.edu

[Pw_forum] how to control the writing of wavefunction

[xu yuehua]

thank you for your detailed analysis.  your guess is right .my outdir is set
to a place,not local to the nodes.i know the reason of my slow job,although
i did not know it through.
as for how to use a local directory as outdir ,it seems another new thing
for me.
would it be possible to tell me about that ?
thank you in advance



your sincerely
 xuyuehua

2007/12/13, Lorenzo Paulatto :
>
>
> On Thu, December 13, 2007 13:42, xu yuehua wrote:
> > yes,maybe once i set  disk_io="none" ,when something goes wrong ,like
> > power
> > is off suddenly,you have to start from  scratch .from this point ,it is
> > wasting time in deed.
> > but is there  an better idea ?
> > i am wondering
>
> I think it is highly unlikely that you have more RAM than disk space, so
> disk space should be no issue. Furthermore it should not be so slow, as
> long as you are leaving wfc_collect=.false. which is the default.
>
> From these assumptions I can guess that you are using a network share as
> temporary directory for your calculation; in other words your outdir is
> set to some place, probably in you home directory, which is not local to
> nodes but stays on a server and is shared via NFS (network file system).
>
> If this is your case, every time wavefunctions are written the data has to
> pass trough the network, it is somehow equivalent to collect_wfc=.true.
> but done externally by the operating system. Furthermore if you are using
> the same network for NFS and mpi when the traffic from NFS suddenly bursts
> it is likely to conflict with mpi and slow it down a lot.
>
> To avoid this problem you must use a local directory as outdir (like
> /tmp), but you to have to remember that if you want to restart a job you
> have to use exactly the same node you used before in order for them to
> find their wavefunctions. Otherwise you may have to recollect the data by
> hand, which is probably not trivial (I have never tried).
>
> I hope what I wrote was not already known to you, goodbye.
> --
> Lorenzo Paulatto
> +39 040 3787 511
> http://people.sissa.it/~paulatto/
>
>
> 
> SISSA Webmail https://webmail.sissa.it/
> Powered by SquirrelMail http://www.squirrelmail.org/
>
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>



-- 
Xu Yuehua
physics Department of Nanjing university
China
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[Pw_forum] how to control the writing of wavefunction

[xu yuehua]

yes,maybe once i set  disk_io="none" ,when something goes wrong ,like power
is off suddenly,you have to start from  scratch .from this point ,it is
wasting time in deed.
but is there  an better idea ?
i am wondering


2007/12/13, Lorenzo Paulatto :
>
>
> On Thu, December 13, 2007 09:06, xu yuehua wrote:
> > hi all:
> > in relax ,i do not want to write wavefuntion into disk.for there is no
> > enough space and time wasting.
> > can anyone to tell me how to deal with it ?
>
> I think setting disk_io='none' in the  namelist should do the
> trick, but are you sure it is a good idea?
>
>
> --
> Lorenzo Paulatto
> +39 040 3787 511
> http://people.sissa.it/~paulatto/
>
>
> 
> SISSA Webmail https://webmail.sissa.it/
> Powered by SquirrelMail http://www.squirrelmail.org/
>
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>



-- 
Xu Yuehua
physics Department of Nanjing university
China
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[Pw_forum] CuO, LDA+U, Pseudopots, etc.

[Agostino Migliore]

Hello

I refer to cations in solution (e.g., Fe2+/Fe3+). Indeed, I explored all
parameters and concluded that "the" minimum can be safely found. The only
problem is that for some configuration of the system and some particular
value of the mixing_beta parameter the calculation ends on a local
minimum. In these (indeed infrequent) cases, anyway the (same) minimum is
gotten along a wide range of the mixing_beta parameter, while a higher
minimum (e.g., the energy is 0.01 Ry more, which is significant for my
work) is reached at a particular mixing_beta value.
Let me express my agreement for the consideration about hybridization, on
which I reflected between this email and the previous one.

Agostino

>
> Hi Agostino
>
> what kind of system are you referring to? it must be one with several
> minima. if this is the case I think you get to a different one changing
> whatever parameter in the input just because of (slightly) different
> initial conditions or numerical noise that may bias the system towards a
> different state. I'm not sure what could be a good way to explore them
> all or to bias the system towards the "right" (lowest energy) one. Maybe
> using fractals. (just kidding). Seriously, if one can distinguish
> the minima then one can write a constraint but what is a relevant degree
> of freedom to perturb in general?
>
> Thinking of CuO I have the suspect that in this system the hybridization
> between Cu and O is important (although the electron may still be quite
> localized). If this is the case then the lda+U on atomic orbitals may be
> not a good idea because it will force integer occupations on atomic
> orbitals
> while hybridization requires sharing of electrons between different
> atoms. Probably wannier functions (that Paul was going to try) are a
> better option.
>
> Matteo
>
>
>

[Pw_forum] Local density of electronic entropy

[Agostino Migliore]

Hello

Some useful equations (directly matching your need or providing good
grounds) can be found on Phys. Rev. B 58, 13459 (1998) and other
papers by F?hnle.

Agostino Migliore

>
> On Dec 10, 2007, at 11:52 , Clark Lee wrote:
>
>> I am very appreciated getting some literature or theoretical
>> background
>> about 'local density of electronic entropy'.

[Pw_forum] CuO, LDA+U, Pseudopots, etc.

[Agostino Migliore]

Hello

Also independently of this specific problem, I use the occasion to say
that sometimes, with finite U, the code gets trapped in local minima for
some values of the "mixing_beta" parameter.

Agostino Migliore

[Pw_forum] CuO, LDA+U, Pseudopots, etc.

[Matteo Cococcioni]

Hi Agostino

what kind of system are you referring to? it must be one with several 
minima. if this is the case I think you get to a different one changing 
whatever parameter in the input just because of (slightly) different 
initial conditions or numerical noise that may bias the system towards a 
different state. I'm not sure what could be a good way to explore them 
all or to bias the system towards the "right" (lowest energy) one. Maybe 
using fractals. (just kidding). Seriously, if one can distinguish 
the minima then one can write a constraint but what is a relevant degree 
of freedom to perturb in general?

Thinking of CuO I have the suspect that in this system the hybridization 
between Cu and O is important (although the electron may still be quite 
localized). If this is the case then the lda+U on atomic orbitals may be 
not a good idea because it will force integer occupations on atomic orbitals
while hybridization requires sharing of electrons between different 
atoms. Probably wannier functions (that Paul was going to try) are a 
better option.

Matteo



Agostino Migliore wrote:
> Hello
>
> Also independently of this specific problem, I use the occasion to say
> that sometimes, with finite U, the code gets trapped in local minima for
> some values of the "mixing_beta" parameter.
>
> Agostino Migliore
>
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>   

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[Pw_forum] Local density of electronic entropy

[Agostino Migliore]

Hello

Some useful equations (directly matching your need or providing good
grounds) can be found on Phys. Rev. B 58, 13459 (1998) and other
papers by F?hnle.

Agostino Migliore

>
> On Dec 10, 2007, at 11:52 , Clark Lee wrote:
>
> I am very appreciated getting some literature or theoretical
> background
> about 'local density of electronic entropy'.

[Pw_forum] how to control the writing of wavefunction

[xu yuehua]

hi all:
in relax ,i do not want to write wavefuntion into disk.for there is no
enough space and time wasting.
can anyone to tell me how to deal with it ?

thank you in advance
-- 
Xu Yuehua
physics Department of Nanjing university
China
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[Pw_forum] how to control the writing of wavefunction

[Lorenzo Paulatto]

On Thu, December 13, 2007 15:06, xu yuehua wrote:
> thank you for your detailed analysis.  your guess is right .my outdir is
> set
> to a place,not local to the nodes.i know the reason of my slow
> job,although
> i did not know it through.
> as for how to use a local directory as outdir ,it seems another new thing
> for me.
> would it be possible to tell me about that ?
> thank you in advance


You let's assume you can write in the /tmp directory on all the nodes
(usually you can) you can use a subdirectory of /tmp as outdir, let's say
/tmp/xy-job

Just set outdir='/tmp/xy-job' in the control namelist. The directory has
to exist on every node.

It is boring to create them by hand you can use ssh with (password-less)
pubkey and some bash cycle, or you can use expect.. you could also try to
use mpirun in some creative way, like
  mpirun -np 8 mkdir -p /tmp/xy-job
but I wouldn't bet on this to work.

I hope this helps
-- 
Lorenzo Paulatto
+39 040 3787 511
http://people.sissa.it/~paulatto/



  SISSA Webmail https://webmail.sissa.it/
  Powered by SquirrelMail http://www.squirrelmail.org/

[Pw_forum] IFC's and eigendisplacements in example06

[Stefano Baroni]

Dear ?mer:

> 1) Could you give me some analysis and explanations on the range of  
> the interatomic force constants (IFC's) for AlAs in example06.
>  On the Forum, there are  some informations and explanations but i  
> don't understand them. I need more explanations.

ask a question and we will try to answer. "give me some explanations"  
is not a question. We could give many explanations to problems that  
you do not have, so we would waste my time. In the lack of any hints  
on what your problem is, the best advice I can give you is to study  
some classical textbooks on lattice dynamics (such as Born and Huang)

>  2) Is there a meaning of ratio of displacement of the two ions (Al  
> and As) in the eigendisplacement pattern?

the meaning is that they are normal modes in the sense that is  
explained in the "small vibrations" chapter of any classical mechanics  
textbook (such as, e.g. Landau or Goldstein)

> The calculated vibrational eigenvectors at X point are below. How  
> can we evaluate this data?

what do you want to evaluate?

SB
>

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

Please, if possible, don't  send me MS Word or PowerPoint attachments
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[Pw_forum] Strange phonon branches appear in phonon dispersion

[Viet Bac]

0.7903  300.7406
0.00  0.00  2.20
  -63.0506  -49.2247  -40.9136  -23.4729  273.4711  297.0578
0.00  0.00  2.30
  -62.1609  -52.8376  -37.0315  -25.3558  276.5514  293.2015
0.00  0.00  2.40
  -61.8563  -56.2311  -32.5370  -26.2996  280.1674  289.0264
0.00  0.00  2.50
  -61.6387  -57.8617  -29.3445  -27.6304  283.8161  285.1565
0.00  0.00  2.503000
  -61.6384  -57.8633  -29.3391  -27.6341  283.8284  285.1440


   Bac,

--
Phung Viet Bac
Division of Mathematical and Physical Science,
Graduate School of Natural Science and Technology,
Kanazawa University,
Kakuma, Kanazawa 920-1192, JAPAN








>
> your phonon branches are really strange...
> with two atoms I would expect 6 modes per each q-point
>
> stefano
>
>
>
> 6 branches for 2 atom are what one expects (in general 3n branches and 3
> acoustical and 3n-3 optical ones).
>
> However negative values indicate some error in your calculation, dependent
> on the magnitude and system.
> You can impose some sum-rules for the acoustic ones, to force them to be
> 0 at the Gamma point.
>
> Acoustic forces are harder to calculate (smaller forces). In your case I
> would guess up to 15 cm^1 should be ok for the acoustic ones.
> Negative optical ones should not occur.
>
> Best
> Marcel Mohr
>
>
>
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[Pw_forum] bands_FS.x and spin polarized metals

[Huiqun Zhou]

Wow, what a "home computer"! Moor's law hadn't been invented 
at that time, right? :-)

Are there any copyright issue to prevent me from using it in my 
presentation about "concise history of personal computer"?

Thanks for sharing the precious picture with us!

Huiqun Zhou
@Earth Sciences, Nanjing University, China

- Original Message - 
From: "Paolo Giannozzi" 
To: "PWSCF Forum" 
Sent: Thursday, December 13, 2007 5:12 AM
Subject: Re: [Pw_forum] bands_FS.x and spin polarized metals


> 
> On Dec 12, 2007, at 21:58 , Nicola Marzari wrote:
> 
>>> I am old enough to have seen card punchers in action, so the term
>>> "abend" is not unknown to me, but I guess younger people don't
>>> know that it is a shorthand for "abnormal end", on IBM mainframes...
>>
>> What's a mainframe ? Is it like a really, really big ipod ?
> 
> do you remember the picture of the "home computer
> in 2004" you sent me some time ago ?
> http://www.fisica.uniud.it/~giannozz/public/pc2004.jpg
> :-)
> 
> P.
> ---
> Paolo Giannozzi, Dept of Physics, University of Udine
> via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
> 
> 
> 
> ___
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>

[Pw_forum] how to control the writing of wavefunction

[Lorenzo Paulatto]

On Thu, December 13, 2007 13:42, xu yuehua wrote:
> yes,maybe once i set  disk_io="none" ,when something goes wrong ,like
> power
> is off suddenly,you have to start from  scratch .from this point ,it is
> wasting time in deed.
> but is there  an better idea ?
> i am wondering

I think it is highly unlikely that you have more RAM than disk space, so
disk space should be no issue. Furthermore it should not be so slow, as
long as you are leaving wfc_collect=.false. which is the default.

[Pw_forum] CuO, LDA+U, Pseudopots, etc.

[Henning Glawe]

On Wed, Dec 12, 2007 at 11:40:56PM -0800, Paul M. Grant wrote:
> Simplistically, the initial d-state configuration of Cu2+ in CuO by Hund?s
> Rule should be 3d9 (one empty minority spin state state
a hole).   But, with
> nspin=2, lda_plus_u set true, and U=5 eV (arbitrary), the initial minority
> spin occupation gets set to unity, not 4/5 on average (3/5 for Ni and 1/5
> for Fe).  Is this due to occ_loc being set to 10 in tabd.f90 and not 9 (it?s
> 6 for Fe and 8 for Ni)?  The occupation distribution converges to around

as the d shell can be filled with 10 electrons, getting a initial hole into the 
d shell while occ_loc=10 is IMHO impossible.


> functionals have equivalent occupations and give similar results).  When I
> try Cu.pz-d-rrkjus.UPF, with 3d10, 4s1 and 4p-1(!!!), the first scf
> iteration yields individual spin occupations of nearly 5(!!!), and the
> situation gets really ugly thereafter.

I also encountered this problem with this pseudo potential; the problem lies
in the normalization of the 3d wave functions saved in the pp file. if you
search in the archives of the pw forum, you will find a patch for pwscf
allowing to recalculate the norm of the atomic states after the pp file has
been read.

-- 
c u
henning

[Pw_forum] bands_FS.x and spin polarized metals

[Stefano Baroni]

happily enough, different people have a different sense of humor!
i enjoyed very much this thread.
best wishes to you all
S.

On Dec 13, 2007, at 10:14 AM, Marcel Mohr wrote:

> On Thu, 13 Dec 2007, Huiqun Zhou wrote:
>
>> Wow, what a "home computer"! Moor's law hadn't been invented
>> at that time, right? :-)
>> Are there any copyright issue to prevent me from using it in my
>> presentation about "concise history of personal computer"?
>
> Although I liked it very much, too. I showed it to a colleague and  
> he told
> me it is fake.
>
> It is a picture of a sumbarine control station see
> http://www.snopes.com/inboxer/hoaxes/computer.asp
>
> Sorry for being the spoiler
> Marcel
>
>
>
>>
>>
>> Thanks for sharing the precious picture with us!
>>
>> Huiqun Zhou
>> @Earth Sciences, Nanjing University, China
>>
>> - Original Message -
>> From: "Paolo Giannozzi" 
>> To: "PWSCF Forum" 
>> Sent: Thursday, December 13, 2007 5:12 AM
>> Subject: Re: [Pw_forum] bands_FS.x and spin polarized metals
>>
>>
>>>
>>> On Dec 12, 2007, at 21:58 , Nicola Marzari wrote:
>>>
>>>>> I am old enough to have seen card punchers in action, so the term
>>>>> "abend" is not unknown to me, but I guess younger people don't
>>>>> know that it is a shorthand for "abnormal end", on IBM  
>>>>> mainframes...
>>>>
>>>> What's a mainframe ? Is it like a really, really big ipod ?
>>>
>>> do you remember the picture of the "home computer
>>> in 2004" you sent me some time ago ?
>>> http://www.fisica.uniud.it/~giannozz/public/pc2004.jpg
>>> :-)
>>>
>>> P.
>>> ---
>>> Paolo Giannozzi, Dept of Physics, University of Udine
>>> via delle Scienze 208, 33100 Udine, Italy
>>> Phone +39-0432-558216, fax +39-0432-558222
>>>
>>>
>>>
>>> ___
>>> 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 mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum

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

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



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[Pw_forum] about the precision of energy and some extend problem.

[Stefano Baroni]

Dear all: two further comments.

1) I have not seen in detail the output of Xu Yuehua's calculations,  
but I would like to point out that one may have negative frequencies  
even if the atomic forces and crystal stress vanish. Negative  
frequencies are a manifestation of a mechanical instability that may  
occur even when the first derivatives of the energy with respect to  
any possible mechanical distortion of the lattice vanish.

2) I am not myself a native English speaker, and I know by experience  
how much it takes to write in a foreign language. I am also aware that  
the difficulty of writing decent English depends a lot on one's own  
mother tongue. However, I would like to kindly urge contributors to  
this mailing list to read twice their posts and always ask themselves  
very carefully if what they have written can be understood with a fair  
investment of time and attention. Working on one's own way of  
expressing oneself is a very important (and rewarding, rest assured!)  
exercise that non-native English speakers should do.

Best wishes,
SB

On Dec 12, 2007, at 12:11 PM, Hande Ustunel wrote:

> Dear Xu Yuehua,
>
> You should fit your energies to a parabola and find the minimum of the
> fit. For a second order fit, your minimum is at about 2.83. 2.77 is  
> just a
> local blip in your rather jumpy data. You cannot decide by looking  
> at the
> individual energies because they do not follow a smooth function.  
> But even
> for the "wrong" lattice constant, there's no physical reason why you  
> should
> get negative frequencies if you have converged your electronic and  
> atomic
> coordinates to high accuracy. I'm attaching the fit as an example.
>
> I would also suggest increasing your cutoff a little because your  
> data, as
> I said, is a bit noisy near the minimum.
>
> Best,
> Hande
>
> On Wed, 12 Dec 2007, xu yuehua wrote:
>
>> hi ,uesers here :
>> i relax one crystal lattice vs energy:
>> i have compute several energy list :
>>
>> c  E(RY)
>> 2.795  -137.79266
>> 2.78   -137.79248
>> 2.77   -137.79233
>> 2.8 -137.7927
>> 2.81  -137.79275
>> 2.82  -137.79275
>> 2.83  -137.79278
>> 2.84  -137.79276
>> 2.85  -137.79279
>> 2.86  -137.79272
>> 2.87  -137.79265
>> 2.88  -137.79258
>> 2.9   -137.79229
>> 2.95  -137.79122
>> these energy points are smooth and  can be plotted  parabola.
>> the system has 12 atoms.the energy is different most at the third  
>> digit
>> after radix point. so i think the average energy/atom is less 0.0001.
>>
>> i want to ask  the  within the precision of energy(my thinking is  
>> based on
>> that :my above calculation is set ecutwfc:29, ecutrho:200,and the   
>> criterion
>> is 35,350, the convergence is 0.0049345 ry.)
>> so this small difference of energy can skip,i.e we can choose 2.77  
>> which is
>> regarded as the best structure?
>> as why i ask this question,for the the structure of 2.85 has two  big
>> negative frequencies  near -100cm-1, even if i add asr .
>> but 2.77 has no negative frequency after i add asr.
>>
>>
>>
>
> -- 
> Hande Ustunel
> Department of Physics
> Office 439
> Middle East Technical University
> Ankara 06531, Turkey
> Tel : +90 312 210 3264
> http://www.physics.metu.edu.tr/~hande
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---
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Trieste
[+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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[Pw_forum] FW: about Fermi Energy shift in periodic (q=0) perturbations

[Stefano de Gironcoli]

we are interested in the limit for q->0.

in this limit the total number of electrons does not change and the 
Fermi energy does not shift (since it is a q/=0 calculation) however the
delta_n(q) = \sum_G chi(q,q+G) deltaV_0(q+G)
 = \sum_G chi0(q,q+G) [deltaV_0(q+G) + 4pi/(q+G)^2 
delta_n(q+G)]

Now chi0(q,q) for metals is FINITE in the limit of q->0 (related to the 
DOS at the FE) and 4pi/q**2 explodes thus the only way things can still 
satisfy the above relation is that n(q) -> 0 quadratically so that
1) the limit for 4pi/q**2 delta_n(q) gives a FINITE contibution to the 
potential V_scf(q->0) that toghether with the other component of the 
response makes that
2) the system is neutral ... i.e. n(q)->0.

In a q==0 calculation the FINITE value of V_scf(q=0) coming from the 
Coulomb potential cannot be calculated calculated directly from 
condition 1) since q==0 and the above ratio is ill defined but can be 
determined by condition 2) ... whether you want to call it a potential 
shift or an (opposite) FE shift is up to you. This latter choice is made 
in the phonon code.

Hope this helps,

 stefano


Ezad Shojaee wrote:
>
> Dear Mr. Gironcoli
>
> Thanx for your answer, but sorry I'm not sure i follow you, could you 
> open it more?!
>
> you mean in the case of periodic perturbation(like the constant one) 
> we have a change in the # of electrons? what exactly happens in this 
> case, so we have to shift the Fermi energy(in order to have neutrality 
> condition)? What happens if we do not shift it(As you see i want you 
> to answer the question you made!)?
>
> Thanx again
>
>  
> Ezad Shojaee - Tehran University
>  
>
> > At any q/=0 the perturbation is such that the number of electrons does
> > not change.
> > Even in the limit of q->0 the macroscopic term in the density response
> > is zero (because in a metal
> > the dielectic constant is infinite).
> > Now consider the case of a periodic (q=0) perturbation, the simplest
> > one, a constant, threated with or w/o the FE shift... which of the two
> > treatments corresponds to the result you would obtain in the liimit 
> q->0 ?
>
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[Pw_forum] how to control the writing of wavefunction

[Lorenzo Paulatto]

On Thu, December 13, 2007 09:06, xu yuehua wrote:
> hi all:
> in relax ,i do not want to write wavefuntion into disk.for there is no
> enough space and time wasting.
> can anyone to tell me how to deal with it ?

I think setting disk_io='none' in the  namelist should do the
trick, but are you sure it is a good idea?


-- 
Lorenzo Paulatto
+39 040 3787 511
http://people.sissa.it/~paulatto/



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[Pw_forum] bands_FS.x and spin polarized metals

[Marcel Mohr]

On Thu, 13 Dec 2007, Huiqun Zhou wrote:

> Wow, what a "home computer"! Moor's law hadn't been invented
> at that time, right? :-)
> Are there any copyright issue to prevent me from using it in my
> presentation about "concise history of personal computer"?

Although I liked it very much, too. I showed it to a colleague and he told 
me it is fake.

It is a picture of a sumbarine control station see 
http://www.snopes.com/inboxer/hoaxes/computer.asp

Sorry for being the spoiler
Marcel



>
>
> Thanks for sharing the precious picture with us!
>
> Huiqun Zhou
> @Earth Sciences, Nanjing University, China
>
> - Original Message -
> From: "Paolo Giannozzi" 
> To: "PWSCF Forum" 
> Sent: Thursday, December 13, 2007 5:12 AM
> Subject: Re: [Pw_forum] bands_FS.x and spin polarized metals
>
>
>>
>> On Dec 12, 2007, at 21:58 , Nicola Marzari wrote:
>>
 I am old enough to have seen card punchers in action, so the term
 "abend" is not unknown to me, but I guess younger people don't
 know that it is a shorthand for "abnormal end", on IBM mainframes...
>>>
>>> What's a mainframe ? Is it like a really, really big ipod ?
>>
>> do you remember the picture of the "home computer
>> in 2004" you sent me some time ago ?
>> http://www.fisica.uniud.it/~giannozz/public/pc2004.jpg
>> :-)
>>
>> P.
>> ---
>> Paolo Giannozzi, Dept of Physics, University of Udine
>> via delle Scienze 208, 33100 Udine, Italy
>> Phone +39-0432-558216, fax +39-0432-558222
>>
>>
>>
>> ___
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>>
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>

[Pw_forum] Strange phonon branches appear in phonon dispersion

[Marcel Mohr]

>>
>> Dear Dr. Stefano and Dr. Mohr,
^^
That is too much honour for me as I am still working on these two letters.

The input below looks ok for me, but two things:

1.) for electronic wavefunctions you choose a 4 4 40 grid. It should be no 
difference to a 1 1 40 one (because of 1 dim, there are no bloch waves 
perp to your wire axis)

2.) your   tr2_ph=1.0d-14 is maybe too small. try to use a value around 
1.0d-20

What about the convergence of the other parameters (ecutwfc)
with respect to your phonon frequencies?

Maybe you find some information in the paper verstraete PhysRevB 74 153408 
(2006).


Best Marcel


>
>
> Thank you for your  comments,
>
> Actually I had successfully  done  phonon dispersion and  EPC  for Al bulk
> structure with  good  results so from now I want to apply for the Al wires
> structures. Firstly I calculate for 2 atom cell of Al with zigzag wires, and
> I got 6 phonon modes along q-points and appear some negative frequencies, so
> I tried to improve my calculation but always appear negative acoustic
> frequencies (optical branch is no problem) and then I did with 4, 6 atom
> cell and of course I got 3-n modes but my results still no good like I
> expect. :(
> To check my set up parameters I calculate the same procedure for Al 1D
> linear chain with 1 and 2 atom cell with hopefully the phonon curves will be
> the same as I studied theoretically in Solid States books, but it was not
> :(. So should my calculation be wrong with this system. Could you give me
> advice about my input parameters? Please keep your eyes my INPUT files (in
> case of 2 atoms in zigzag chain)
>
> Al.scf.fit.in
>
> 
>   ibrav = 6,
> celldm(1) = 39.994,
>   celldm(3) =  0.199762906,
> nat = 2,
>ntyp = 1,
> ecutwfc = 25.D0 ,
> ecutrho = 300,
> occupations = 'smearing' ,
> degauss = 0.05 ,
>smearing = 'methfessel-paxton' ,
>  la2F = .true.
> /
> 
>conv_thr = 1.D-10 ,
> mixing_beta = 0.7D0 ,
> /
> ATOMIC_SPECIES
>   Al   26.98000  Al.vbc.UPF
> ATOMIC_POSITIONS angstrom
> Al   0.0   1.517315647   2.138739361
> Al   0.0   0.116702849   0.023699809
> K_POINTS automatic
>  4 4 40   0 0 0
>
> Al.scf.in
>
> 
>   ibrav = 6,
> celldm(1) = 39.994,
>   celldm(3) =  0.199762906,
> nat = 2,
>ntyp = 1,
> ecutwfc = 25.D0 ,
> ecutrho = 300,
> occupations = 'smearing' ,
> degauss = 0.05 ,
>smearing = 'methfessel-paxton'
> /
> 
>conv_thr = 1.D-10 ,
> mixing_beta = 0.7D0 ,
> /
> ATOMIC_SPECIES
>   Al   26.98000  Al.vbc.UPF
> ATOMIC_POSITIONS angstrom
> Al   0.0   1.517315647   2.138739361
> Al   0.0   0.116702849   0.023699809
> K_POINTS automatic
>  2 2 20   0 0 0
>
> Al.elph.in
>
> Electron-phonon coefficients for Alwire_2
> 
>  tr2_ph=1.0d-14,
>  prefix='al2_elph',
>  fildvscf='al2d',
>  filelph='matrix'
>  amass(1)=26.98,
>  outdir='/root/tmp/',
>  fildyn='al2m.dyn',
>  elph=.true.,
>  trans=.true.,
>  ldisp=.true.
>  nq1=1, nq2=1, nq3=10,
>
> And hereafter 6 modes I got
>
>  nbnd=   6, nks=  27 /
>0.00  0.00  0.00
>   -0.0855   -0.04500.   20.7938  196.2309  372.4942
>0.00  0.00  0.10
>  -13.14325.66575.7114   20.3098  196.7060  372.0899
>0.00  0.00  0.20
>  -25.6753   10.2550   10.5805   18.8468  198.1533  371.0008
>0.00  0.00  0.30
>  -37.6999   14.0728   14.1858   16.2544  200.5950  369.4869
>0.00  0.00  0.40
>  -48.8295   11.6034   16.4265   16.4576  203.9728  367.7201
>0.00  0.00  0.50
>  -58.7192   -5.6944   16.7453   17.6129  208.1190  365.6663
>0.00  0.00  0.60
>  -67.0895  -15.3952   14.9673   18.4203  212.8051  363.1793
>0.00  0.00  0.70
>  -73.7443  -21.7038   11.9605   19.3942  217.8126  360.1938
>0.00  0.00  0.80
>  -78.6120  -26.99489.8326   20.4642  222.9635  356.8134
>0.00  0.00  0.90
>  -81.7857  -31.7595   10.1665   21.2176  228.1041  353.2106
>0.00  0.00  1.00
>  -83.4878  -36.1149   10.5785   21.4924  233.0809  349.4591
>0.00  0.00  1.10
>  -83.9637  -39.93806.4409   21.5912  237.7521  345.4939
>0.00  0.00  1.20
>  -83.3549  -43.0700  -11.8614   21.8643  242.0400  341.2345
>0.00  0.00  1.30
>  -81.7148  -45.5109  -19.5363   22.1233  245.9755  336.7214
>0.00  0.00  1.40
>  

[Pw_forum] bands_FS.x and spin polarized metals

[Paul M. Grant]

Paolo, I'm sure I'm older than you!

You're absolutely right.  Abend was coined by the designers of the IBM 701.
Mean time to failure on the early prototypes of that machine was only about
three hours.

Paul M. Grant, PhD
Principal, W2AGZ Technologies
Visiting Scholar, Applied Physics, Stanford University
EPRI Science Fellow (Retired)
IBM Research Staff Member Emeritus
w2agz at pacbell.net
http://www.w2agz.com
?
?


-Original Message-
From: pw_forum-bounces at pwscf.org [mailto:pw_forum-boun...@pwscf.org] On
Behalf Of Paolo Giannozzi
Sent: Wednesday, December 12, 2007 12:50 PM
To: PWSCF Forum
Subject: Re: [Pw_forum] bands_FS.x and spin polarized metals


On Dec 12, 2007, at 21:32 , Paul M. Grant wrote:

> And sure enough, if you?re dumb and try anyway, it abends with a  
> read error
>

I am old enough to have seen card punchers in action, so the term
"abend" is not unknown to me, but I guess younger people don't
know that it is a shorthand for "abnormal end", on IBM mainframes...

Paolo
---
Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222



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[Pw_forum] Optical properties

[yupiaofei(SDU)]

Hi, everybody!

I'm trying to perform a calculation for the optical properties of a bulk 
material. As we know, it can obtain it form the imaginary part of the 
dielectric constant. but I don't know if the PWSCF code could do this.

Have anybody done this before?



Kesong Yang

School of Physics and Microelectronics

Shandong University, Jinan 250100, People?s Republic of China


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[Pw_forum] FW: about Fermi Energy shift in periodic (q=0) perturbations

[Ezad Shojaee]

 
Dear Mr. Gironcoli
Thanx for your answer, but sorry I'm not sure i follow you, could you open it 
more?!
you mean in the case of periodic perturbation(like the constant one) we have a 
change in the # of electrons? what exactly happens in this case, so we have to 
shift the Fermi energy(in order to have neutrality condition)? What happens if 
we do not shift it(As you see i want you to answer the question you made!)?
Thanx again
 
Ezad Shojaee - Tehran University
 
> At any q/=0 the perturbation is such that the number of electrons does > not 
> change.> Even in the limit of q->0 the macroscopic term in the density 
> response > is zero (because in a metal> the dielectic constant is infinite).> 
> Now consider the case of a periodic (q=0) perturbation, the simplest > one, a 
> constant, threated with or w/o the FE shift... which of the two > treatments 
> corresponds to the result you would obtain in the liimit q->0 ?
___> Pw_forum mailing list> Pw_forum at 
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[Pw_forum] IFC's and eigendisplacements in example06

[Ömer Koç]

Dear PWSCF users,


My questions are about example06

 1) Could you give me some analysis and explanations on the range of the
interatomic force constants (IFC's) for AlAs in example06.
 On the Forum, there are  some informations and explanations but i don't
understand them. I need more explanations.



alas444.fc



  2 2  2 10.500  0.000  0.000  0.000   0.000
0.000

   1   'Al '24590.7655930491

   2   'As '68285.4024548272

1 1  0.000  0.000  0.000

2 2  0.250  0.250  0.250

 T

 13.7439581   0.000  0.000

  0.000  13.7439581  0.000

  0.000   0.000 13.7439581

1

  2.5582103   0.000  0.000

  0.000   2.5582103  0.000

  0.000   0.000  2.5582103

2

 -2.5582103   0.000  0.000

  0.000  -2.5582103  0.000

  0.000   0.000 -2.5582103

   44   4

   11   1   1

   11   1   2.17004984418E-01

   21   1  -5.06952740903E-03

   31   1   9.99492789182E-05

   41   1  -5.06952740903E-03

   12   1   1.07967422105E-02

   22   1  -6.07584921925E-04

   32   1  -1.61474518909E-04

   42   1  -5.06952740903E-03

   13   1   4.18136269798E-03

   23   1  -6.07584921925E-04

   33   1   9.99492789182E-05

   43   1  -6.07584921925E-04

   14   1   1.07967422105E-02

   24   1  -5.06952740903E-03

   34   1  -1.61474518909E-04

   44   1  -6.07584921925E-04

   11   2  -5.06952740903E-03

   21   2  -1.61474518909E-04

   31   2  -6.07584921925E-04

   




2) Is there a meaning of ratio of displacement of the two ions (Al and As)
in the eigendisplacement pattern?
The calculated vibrational eigenvectors at X point are below. How can we
evaluate this data?



q =   0.   0.  1.

 **

 omega( 1) =2.841119 [THz] =  94.770143 [cm-1]

 (   0.611885   0.039292-0.353070  -0.018348 0.000.00
) Al

 ( -0.352406   -0.018313 0.610733   0.039218 0.00   0.00)
As

 omega( 2) =2.841119 [THz] =  94.770143 [cm-1]

 (   0.353530   0.003400 0.613143  -0.001588  0.000.00
)

 (   0.611989  -0.001585 0.352865   0.003394 0.000.00
)

 omega( 3) =6.563802 [THz] = 218.946309 [cm-1]

 (   0.00   0.00 0.00   0.00 0.000.00
)

 (   0.00   0.00 0.00   0.00 1.000.00
)

 omega( 4) =   10.442067 [THz] = 348.312171 [cm-1]

 (   0.753056   0.016289-0.563430   0.002731 0.000.00
)

 (   0.203284  -0.000985-0.271700  -0.005877 0.000.00
)

 omega( 5) =   10.442067 [THz] = 348.312171 [cm-1]

 ( -0.563178   -0.017050-0.753227  -0.002855 0.00   0.00
)

 (   0.271762   0.001030 0.203193   0.006152 0.000.00
)

 omega( 6) =   12.209736 [THz] = 407.275646 [cm-1]

 (   0.00   0.00 0.00   0.00-0.1382590.990396
)

 (   0.00   0.00 0.00   0.00 0.000.00
)

 **

 diagonalizing the dynamical matrix ...

Many thanks in advance

?mer.

-- 
?mer Ko?
100. Y?l University
Dept of Physics Van, Turkey
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[Pw_forum] CuO, LDA+U, Pseudopots, etc.

[Matteo Cococcioni]

Dear Paul,

I have no experience with CuO and can't give you a very useful  
advise. I suspect that even if you change occ_loc = 9 for Cu the
code will converge to the same ground state. This is however quick to  
try and you may find better results (sometimes the code gets trapped in
local minima with a finite U).

On Dec 13, 2007, at 6:26 AM, Henning Glawe wrote:

> On Wed, Dec 12, 2007 at 11:40:56PM -0800, Paul M. Grant wrote:
>> Simplistically, the initial d-state configuration of Cu2+ in CuO  
>> by Hund?s
>> Rule should be 3d9 (one empty minority spin state state?a hole).
>> But, with
>> nspin=2, lda_plus_u set true, and U=5 eV (arbitrary), the initial  
>> minority
>> spin occupation gets set to unity, not 4/5 on average (3/5 for Ni  
>> and 1/5
>> for Fe).  Is this due to occ_loc being set to 10 in tabd.f90 and  
>> not 9 (it?s
>> 6 for Fe and 8 for Ni)?  The occupation distribution converges to  
>> around
>
> as the d shell can be filled with 10 electrons, getting a initial  
> hole into the
> d shell while occ_loc=10 is IMHO impossible.
>
>
>> functionals have equivalent occupations and give similar  
>> results).  When I
>> try Cu.pz-d-rrkjus.UPF, with 3d10, 4s1 and 4p-1(!!!), the first scf
>> iteration yields individual spin occupations of nearly 5(!!!), and  
>> the
>> situation gets really ugly thereafter.
>
> I also encountered this problem with this pseudo potential; the  
> problem lies
> in the normalization of the 3d wave functions saved in the pp file.  
> if you
> search in the archives of the pw forum, you will find a patch for  
> pwscf
> allowing to recalculate the norm of the atomic states after the pp  
> file has
> been read.
>


the patch has been implemented in the cvs version of the code. if you  
download it and read INPUT_PW
you find the following lines (you are interested in norm-atomic):


U_projection_type   CHARACTER   (default='atomic')
Only active when lda_plus_U is .true., specifies the  
type
of projector on localized orbital to be used in the  
LDA+U
scheme.
Currently available choices:
'atomic': use atomic wfc's (as they are) to build the  
projector
'ortho-atomic': use Lowdin orthogonalized atomic wfc's
'norm-atomic': Lowdin normalization of atomic wfc.  
Keep in mind:
   atomic wfc are not orthogonalized in  
this case.
   This is a "quick and dirty" trick to  
be used when
   atomic wfc from the pseudopotential  
are not
   normalized (and thus produce  
occupation whose
   value exceeds unity). If  
orthogonalized wfc are
   not needed always try 'atomic' first.
'file': use the information from file "prefix".atwfc  
that must
have been generated previously, for instance  
by pmw.x
(see PP/poormanwannier.f90 for details)
NB: forces and stress currently implemented only for the
'atomic' choice.


Hope this helps.

Matteo


> -- 
> c u
> henning
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[Pw_forum] Optical properties

[Andrea Benassi]

Hi Kesong,
you can find a post processing named epsilon.f90, you have to compile it
separately doing "make epsilon.x" from the PP folder. In the DOCS folder you
can also find a manual that explane how the code works and all the possible
options.
Let me know if you face some problems.
best regards.
Andrea


-- 
Andrea Benassi
National Research Center S3, CNR-INFM  ( http://www.s3.infm.it )
Dipartimento di Fisica, Universita' di Modena e Reggio Emilia
Via Campi 213/A I-41100 Modena, Italy
Tel: +39 059 2055314
Fax: +39 059 374794
E-mail:  benassi.andrea at unimore.it
URL: http://www.nanoscience.unimo.it
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