[Pw_forum] where is the end of an unconverged NEB calculation
vega lew
quantumdft at gmail.com
Fri Nov 6 10:35:00 CET 2009
Dear frined in CAS,
My convergence of every single NEB iteration is very well. My convergence
problem is about the calculated "activation energy" (I call it as energy
barrier in last mail.), not for the energy convergence of every image.
here is a few lines from my output file,
Program PWSCF v.4.0.3 starts ...
Today is 8Oct2009 at 23:53:20
Parallel version (MPI)
Number of processors in use: 5
path-images division: nimage = 5
For Norm-Conserving or Ultrasoft (Vanderbilt) Pseudopotentials or PAW
Current dimensions of program pwscf are:
Max number of different atomic species (ntypx) = 10
Max number of k-points (npk) = 40000
Max angular momentum in pseudopotentials (lmaxx) = 3
gamma-point specific algorithms are used
initial path length = 7.8290 bohr
initial inter-image distance = 1.3048 bohr
calculation = neb
restart_mode = from_scratch
opt_scheme = quick-min
num_of_images = 7
nstep = 9999
CI_scheme = no-CI
first_last_opt = F
coarse-grained phase-space = F
use_freezing = F
ds = 1.0000 a.u.
k_max = 0.1000 a.u.
k_min = 0.1000 a.u.
suggested k_max = 0.6169 a.u.
suggested k_min = 0.6169 a.u.
path_thr = 0.0500 eV / A
------------------------------ iteration 1
------------------------------
cpu = 0 tcpu = 0.2 self-consistency for image 1
cpu = 3 tcpu = 0.2 self-consistency for image 5
cpu = 4 tcpu = 0.2 self-consistency for image 6
cpu = 2 tcpu = 0.2 self-consistency for image 4
cpu = 1 tcpu = 0.2 self-consistency for image 7
cpu = 0 tcpu = 23616.8 self-consistency for image 2
cpu = 1 tcpu = 25603.1 self-consistency for image 3
activation energy (->) = 3.272591 eV
activation energy (<-) = 2.990961 eV
image energy (eV) error (eV/A) frozen
1 -119085.6620746 0.024462 T
2 -119084.9563724 2.640583 F
3 -119083.3975295 2.385012 F
4 -119082.3894835 2.896402 F
5 -119083.2192599 2.998904 F
6 -119084.7252314 2.403066 F
7 -119085.3804446 0.025165 T
path length = 7.829 bohr
inter-image distance = 1.305 bohr
------------------------------ iteration 2
------------------------------
cpu = 2 tcpu = 29648.3 self-consistency for image 4
cpu = 0 tcpu = 42567.1 self-consistency for image 2
cpu = 1 tcpu = 44477.8 self-consistency for image 3
cpu = 3 tcpu = 30626.8 self-consistency for image 5
cpu = 4 tcpu = 32197.2 self-consistency for image 6
activation energy (->) = 3.093816 eV
activation energy (<-) = 2.812186 eV
image energy (eV) error (eV/A) frozen
1 -119085.6620746 0.024462 T
2 -119085.0987352 2.105271 F
3 -119083.6078363 2.170459 F
4 -119082.5682586 2.050101 F
5 -119083.5224117 1.596776 F
6 -119084.8769055 1.343862 F
7 -119085.3804446 0.025165 T
path length = 7.843 bohr
inter-image distance = 1.307 bohr
......
......
------------------------------ iteration 120
------------------------------
cpu = 2 tcpu = ******** self-consistency for image 4
cpu = 0 tcpu = ******** self-consistency for image 2
cpu = 3 tcpu = ******** self-consistency for image 5
cpu = 4 tcpu = ******** self-consistency for image 6
cpu = 1 tcpu = ******** self-consistency for image 3
activation energy (->) = 1.786596 eV
activation energy (<-) = 1.504966 eV
image energy (eV) error (eV/A) frozen
1 -119085.6620746 0.024462 T
2 -119085.4786718 0.223126 F
3 -119083.9049529 0.170985 F
4 -119083.8754787 0.076161 F
5 -119085.1083173 0.075946 F
6 -119085.3050720 0.015511 F
7 -119085.3804446 0.025165 T
path length = 9.729 bohr
inter-image distance = 1.621 bohr
------------------------------ iteration 121
------------------------------
cpu = 2 tcpu = ******** self-consistency for image 4
cpu = 3 tcpu = ******** self-consistency for image 5
cpu = 0 tcpu = ******** self-consistency for image 2
cpu = 4 tcpu = ******** self-consistency for image 6
cpu = 1 tcpu = ******** self-consistency for image 3
activation energy (->) = 1.775789 eV
activation energy (<-) = 1.494159 eV
image energy (eV) error (eV/A) frozen
1 -119085.6620746 0.024462 T
2 -119085.4781477 0.130868 F
3 -119083.8862860 0.275250 F
4 -119083.8905252 0.089256 F
5 -119085.1088347 0.047586 F
6 -119085.3051231 0.015512 F
7 -119085.3804446 0.025165 T
path length = 9.725 bohr
inter-image distance = 1.621 bohr
------------------------------ iteration 122
------------------------------
cpu = 2 tcpu = ******** self-consistency for image 4
cpu = 3 tcpu = ******** self-consistency for image 5
cpu = 0 tcpu = ******** self-consistency for image 2
cpu = 1 tcpu = ******** self-consistency for image 3
cpu = 4 tcpu = ******** self-consistency for image 6
activation energy (->) = 1.791716 eV
activation energy (<-) = 1.510086 eV
image energy (eV) error (eV/A) frozen
1 -119085.6620746 0.024462 T
2 -119085.4766388 0.150020 F
3 -119083.8703582 0.360096 F
4 -119083.9053588 0.136487 F
5 -119085.1096015 0.054464 F
6 -119085.3051878 0.017319 F
7 -119085.3804446 0.025165 T
......
......
......
------------------------------ iteration 160
------------------------------
cpu = 2 tcpu = ******** self-consistency for image 4
cpu = 0 tcpu = ******** self-consistency for image 2
cpu = 3 tcpu = ******** self-consistency for image 5
cpu = 1 tcpu = ******** self-consistency for image 3
cpu = 4 tcpu = ******** self-consistency for image 6
activation energy (->) = 2.015566 eV
activation energy (<-) = 1.733936 eV
image energy (eV) error (eV/A) frozen
1 -119085.6620746 0.024462 T
2 -119085.4084826 0.122618 F
3 -119083.6465085 0.151901 F
4 -119084.1207907 0.114239 F
5 -119085.1378794 0.024820 F
6 -119085.3093981 0.014540 F
7 -119085.3804446 0.025165 T
path length = 9.760 bohr
inter-image distance = 1.627 bohr
------------------------------ iteration 161
------------------------------
cpu = 2 tcpu = ******** self-consistency for image 4
cpu = 3 tcpu = ******** self-consistency for image 5
cpu = 0 tcpu = ******** self-consistency for image 2
cpu = 4 tcpu = ******** self-consistency for image 6
cpu = 1 tcpu = ******** self-consistency for image 3
activation energy (->) = 2.019415 eV
activation energy (<-) = 1.737785 eV
image energy (eV) error (eV/A) frozen
1 -119085.6620746 0.024462 T
2 -119085.4066890 0.190727 F
3 -119083.6426594 0.205492 F
4 -119084.1216091 0.058992 F
5 -119085.1383781 0.022947 F
6 -119085.3094981 0.024415 F
7 -119085.3804446 0.025165 T
path length = 9.765 bohr
inter-image distance = 1.627 bohr
......
......
......
as I said last mail, the activation energy goes to 1.49 eV from the intial
2.99 eV in about 120 iterations. Then the energy barrier rise to 1.73 eV bit
by bit in following 40 iterations. And the calculation is still running
while this value is still going up.
How could I deal with this?
thank you for reading and reply
best,
vega
On Fri, Nov 6, 2009 at 4:50 PM, lfhuang <lfhuang at theory.issp.ac.cn> wrote:
> Dear vega lew:
> Have you gone into the ./tmp directory to see the energy convergence of
> every image? The calculational statuses of all the images can be found
> there, and I guess your convergence problem may be due to the same reasons
> as ordinary electronic structrue calculations, which may be modified by
> change some parameters e.g. k-points numbers, smearing, nband. Or there may
> be some defects in the pseudopotential and you should better change for
> another one. May these be helpful.
>
> Best Wishes!
> Yours Sincerely
> L.F.Huang
>
> > Date: Fri, 6 Nov 2009 11:35:39 +0800
> > From: vega lew
> > Subject: [Pw_forum] where is the end of an unconverged NEB calculation
> > To: PWSCF Forum
> > Message-ID:
> >
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > Dear all,
> >
> > During my NEB calculations, I found there are two possible situation.
> First,
> > the calculation could be converged after about 100 iterations. Second,
> the
> > calculation never converged in more than 300 iterations. And for the
> second
> > case, the energy barrier went down and down to a certain value, and then
> the
> > reported energy barrier went up gradually. For example in my resent job,
> the
> > energy barrier goes to 1.49 eV from the intial 2.99 eV in about 120
> > iterations. Then the energy barrier rise to 1.73 eV bit by bit in
> following
> > 40 iterations. And the calculation is still running while this value is
> > still going up. How could I deal with this situation? Could I take the
> > lowest value as the energy barrier of the reaction? How could I know
> whether
> > there will be another smaller value in the longer calculation?
> >
> > thank you for reading. Ang hints will be deeply appreciated.
> >
> > best,
> >
> > vega
> >
> > --
> >
> ==================================================================================
>
> > Vega Lew ( weijia liu)
> > Graduate student
> > State Key Laboratory of Materials-oriented Chemical Engineering
> > College of Chemistry and Chemical Engineering
> > Nanjing University of Technology, 210009, Nanjing, Jiangsu, China
> >
> ******************************************************************************************************************
>
> > Email: vegalew at gmail.com
> > Office: Room A705, Technical Innovation Building, Xinmofan Road 5#,
> Nanjing,
> > Jiangsu, China
> >
> ******************************************************************************************************************
>
>
> ------
> ======================================================================
> L.F.Huang(黄良锋) ph.D candidate, DFT and phonon physics
> ======================================================================
> Add: Research Laboratory for Computational Materials Sciences,
> Instutue of Solid State Physics,the Chinese Academy of Sciences,
> P.O.Box 1129, Hefei 230031, P.R.China
> Tel: 86-551-5591464-328(office)
> Fax: 86-551-5591434
> Web: http://theory.issp.ac.cn> (website of our theory group)
> http://www.issp.ac.cn> (website of our institute)
> ======================================================================
> <http://www.issp.ac.cn/> <http://theory.issp.ac.cn/>
>
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--
==================================================================================
Vega Lew ( weijia liu)
Graduate student
State Key Laboratory of Materials-oriented Chemical Engineering
College of Chemistry and Chemical Engineering
Nanjing University of Technology, 210009, Nanjing, Jiangsu, China
******************************************************************************************************************
Email: vegalew at gmail.com
Office: Room A705, Technical Innovation Building, Xinmofan Road 5#, Nanjing,
Jiangsu, China
******************************************************************************************************************
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