<div>Dear frined in CAS,</div>
<div> </div>
<div>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.</div>
<div> </div>
<div>here is a few lines from my output file,</div>
<div> </div>
<div> Program PWSCF v.4.0.3 starts ...<br> Today is 8Oct2009 at 23:53:20 <br> <br> Parallel version (MPI)<br> <br> Number of processors in use: 5<br> path-images division: nimage = 5<br>
<br> For Norm-Conserving or Ultrasoft (Vanderbilt) Pseudopotentials or PAW<br> <br> Current dimensions of program pwscf are:<br> Max number of different atomic species (ntypx) = 10<br> Max number of k-points (npk) = 40000<br>
Max angular momentum in pseudopotentials (lmaxx) = 3<br> <br> gamma-point specific algorithms are used<br> <br> <br> initial path length = 7.8290 bohr<br> initial inter-image distance = 1.3048 bohr<br>
<br> calculation = neb<br> restart_mode = from_scratch<br> opt_scheme = quick-min<br> num_of_images = 7<br> nstep = 9999<br>
CI_scheme = no-CI<br> first_last_opt = F<br> coarse-grained phase-space = F<br> use_freezing = F<br> ds = 1.0000 a.u.<br>
k_max = 0.1000 a.u.<br> k_min = 0.1000 a.u.<br> suggested k_max = 0.6169 a.u.<br> suggested k_min = 0.6169 a.u.<br> path_thr = 0.0500 eV / A<br>
<br> ------------------------------ iteration 1 ------------------------------<br> <br> cpu = 0 tcpu = 0.2 self-consistency for image 1<br> cpu = 3 tcpu = 0.2 self-consistency for image 5<br>
cpu = 4 tcpu = 0.2 self-consistency for image 6<br> cpu = 2 tcpu = 0.2 self-consistency for image 4<br> cpu = 1 tcpu = 0.2 self-consistency for image 7<br> cpu = 0 tcpu = 23616.8 self-consistency for image 2<br>
cpu = 1 tcpu = 25603.1 self-consistency for image 3<br> <br> activation energy (->) = 3.272591 eV<br> activation energy (<-) = 2.990961 eV<br> <br> image energy (eV) error (eV/A) frozen<br>
<br> 1 -119085.6620746 0.024462 T<br> 2 -119084.9563724 2.640583 F<br> 3 -119083.3975295 2.385012 F<br> 4 -119082.3894835 2.896402 F<br>
5 -119083.2192599 2.998904 F<br> 6 -119084.7252314 2.403066 F<br> 7 -119085.3804446 0.025165 T<br> <br> path length = 7.829 bohr<br>
inter-image distance = 1.305 bohr<br> <br> ------------------------------ iteration 2 ------------------------------<br> <br> cpu = 2 tcpu = 29648.3 self-consistency for image 4<br> cpu = 0 tcpu = 42567.1 self-consistency for image 2<br>
cpu = 1 tcpu = 44477.8 self-consistency for image 3<br> cpu = 3 tcpu = 30626.8 self-consistency for image 5<br> cpu = 4 tcpu = 32197.2 self-consistency for image 6<br> <br> activation energy (->) = 3.093816 eV<br>
activation energy (<-) = 2.812186 eV<br> <br> image energy (eV) error (eV/A) frozen<br> <br> 1 -119085.6620746 0.024462 T<br> 2 -119085.0987352 2.105271 F<br>
3 -119083.6078363 2.170459 F<br> 4 -119082.5682586 2.050101 F<br> 5 -119083.5224117 1.596776 F<br> 6 -119084.8769055 1.343862 F<br>
7 -119085.3804446 0.025165 T<br> <br> path length = 7.843 bohr<br> inter-image distance = 1.307 bohr<br>......</div>
<div>......</div>
<div> ------------------------------ iteration 120 ------------------------------<br> <br> cpu = 2 tcpu = ******** self-consistency for image 4<br> cpu = 0 tcpu = ******** self-consistency for image 2<br>
cpu = 3 tcpu = ******** self-consistency for image 5<br> cpu = 4 tcpu = ******** self-consistency for image 6<br> cpu = 1 tcpu = ******** self-consistency for image 3<br> <br> activation energy (->) = 1.786596 eV<br>
activation energy (<-) = 1.504966 eV<br> <br> image energy (eV) error (eV/A) frozen<br> <br> 1 -119085.6620746 0.024462 T<br> 2 -119085.4786718 0.223126 F<br>
3 -119083.9049529 0.170985 F<br> 4 -119083.8754787 0.076161 F<br> 5 -119085.1083173 0.075946 F<br> 6 -119085.3050720 0.015511 F<br>
7 -119085.3804446 0.025165 T<br> <br> path length = 9.729 bohr<br> inter-image distance = 1.621 bohr<br> <br> ------------------------------ iteration 121 ------------------------------<br>
<br> cpu = 2 tcpu = ******** self-consistency for image 4<br> cpu = 3 tcpu = ******** self-consistency for image 5<br> cpu = 0 tcpu = ******** self-consistency for image 2<br> cpu = 4 tcpu = ******** self-consistency for image 6<br>
cpu = 1 tcpu = ******** self-consistency for image 3<br> <br> activation energy (->) = 1.775789 eV<br> activation energy (<-) = 1.494159 eV<br> <br> image energy (eV) error (eV/A) frozen<br>
<br> 1 -119085.6620746 0.024462 T<br> 2 -119085.4781477 0.130868 F<br> 3 -119083.8862860 0.275250 F<br> 4 -119083.8905252 0.089256 F<br>
5 -119085.1088347 0.047586 F<br> 6 -119085.3051231 0.015512 F<br> 7 -119085.3804446 0.025165 T<br> <br> path length = 9.725 bohr<br>
inter-image distance = 1.621 bohr<br> <br> ------------------------------ iteration 122 ------------------------------<br> <br> cpu = 2 tcpu = ******** self-consistency for image 4<br> cpu = 3 tcpu = ******** self-consistency for image 5<br>
cpu = 0 tcpu = ******** self-consistency for image 2<br> cpu = 1 tcpu = ******** self-consistency for image 3<br> cpu = 4 tcpu = ******** self-consistency for image 6<br> <br> activation energy (->) = 1.791716 eV<br>
activation energy (<-) = 1.510086 eV<br> <br> image energy (eV) error (eV/A) frozen<br> <br> 1 -119085.6620746 0.024462 T<br> 2 -119085.4766388 0.150020 F<br>
3 -119083.8703582 0.360096 F<br> 4 -119083.9053588 0.136487 F<br> 5 -119085.1096015 0.054464 F<br> 6 -119085.3051878 0.017319 F<br>
7 -119085.3804446 0.025165 T<br>......</div>
<div>......</div>
<div>......<br> ------------------------------ iteration 160 ------------------------------<br> <br> cpu = 2 tcpu = ******** self-consistency for image 4<br> cpu = 0 tcpu = ******** self-consistency for image 2<br>
cpu = 3 tcpu = ******** self-consistency for image 5<br> cpu = 1 tcpu = ******** self-consistency for image 3<br> cpu = 4 tcpu = ******** self-consistency for image 6<br> <br> activation energy (->) = 2.015566 eV<br>
activation energy (<-) = 1.733936 eV<br> <br> image energy (eV) error (eV/A) frozen<br> <br> 1 -119085.6620746 0.024462 T<br> 2 -119085.4084826 0.122618 F<br>
3 -119083.6465085 0.151901 F<br> 4 -119084.1207907 0.114239 F<br> 5 -119085.1378794 0.024820 F<br> 6 -119085.3093981 0.014540 F<br>
7 -119085.3804446 0.025165 T<br> <br> path length = 9.760 bohr<br> inter-image distance = 1.627 bohr<br> <br> ------------------------------ iteration 161 ------------------------------<br>
<br> cpu = 2 tcpu = ******** self-consistency for image 4<br> cpu = 3 tcpu = ******** self-consistency for image 5<br> cpu = 0 tcpu = ******** self-consistency for image 2<br> cpu = 4 tcpu = ******** self-consistency for image 6<br>
cpu = 1 tcpu = ******** self-consistency for image 3<br> <br> activation energy (->) = 2.019415 eV<br> activation energy (<-) = 1.737785 eV<br> <br> image energy (eV) error (eV/A) frozen<br>
<br> 1 -119085.6620746 0.024462 T<br> 2 -119085.4066890 0.190727 F<br> 3 -119083.6426594 0.205492 F<br> 4 -119084.1216091 0.058992 F<br>
5 -119085.1383781 0.022947 F<br> 6 -119085.3094981 0.024415 F<br> 7 -119085.3804446 0.025165 T<br> <br> path length = 9.765 bohr<br>
inter-image distance = 1.627 bohr</div>
<div>......</div>
<div>......</div>
<div>......</div>
<div> </div>
<div>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. </div>
<div> </div>
<div>How could I deal with this?</div>
<div> </div>
<div>thank you for reading and reply</div>
<div> </div>
<div>best,</div>
<div> </div>
<div>vega<br></div>
<div class="gmail_quote">On Fri, Nov 6, 2009 at 4:50 PM, lfhuang <span dir="ltr"><<a href="mailto:lfhuang@theory.issp.ac.cn">lfhuang@theory.issp.ac.cn</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">
<div>
<div>Dear vega lew: <br>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. <br>
<br>Best Wishes! <br>Yours Sincerely <br>L.F.Huang <br><br><font color="#444444">> Date: Fri, 6 Nov 2009 11:35:39 +0800 <br></font><font color="#444444">> From: vega lew <br></font><font color="#444444">> Subject: [Pw_forum] where is the end of an unconverged NEB calculation <br>
</font><font color="#444444">> To: PWSCF Forum <br></font><font color="#444444">> Message-ID: <br></font><font color="#444444">> <br></font><font color="#444444">> Content-Type: text/plain; charset="iso-8859-1" <br>
</font>
<div>
<div></div>
<div class="h5"><font color="#444444">> <br></font><font color="#444444">> Dear all, <br></font><font color="#444444">> <br></font><font color="#444444">> During my NEB calculations, I found there are two possible situation. First, <br>
</font><font color="#444444">> the calculation could be converged after about 100 iterations. Second, the <br></font><font color="#444444">> calculation never converged in more than 300 iterations. And for the second <br>
</font><font color="#444444">> case, the energy barrier went down and down to a certain value, and then the <br></font><font color="#444444">> reported energy barrier went up gradually. For example in my resent job, the <br>
</font><font color="#444444">> energy barrier goes to 1.49 eV from the intial 2.99 eV in about 120 <br></font><font color="#444444">> iterations. Then the energy barrier rise to 1.73 eV bit by bit in following <br></font><font color="#444444">> 40 iterations. And the calculation is still running while this value is <br>
</font><font color="#444444">> still going up. How could I deal with this situation? Could I take the <br></font><font color="#444444">> lowest value as the energy barrier of the reaction? How could I know whether <br>
</font><font color="#444444">> there will be another smaller value in the longer calculation? <br></font><font color="#444444">> <br></font><font color="#444444">> thank you for reading. Ang hints will be deeply appreciated. <br>
</font><font color="#444444">> <br></font><font color="#444444">> best, <br></font><font color="#444444">> <br></font><font color="#444444">> vega <br></font><font color="#444444">> <br></font><font color="#444444">> -- <br>
</font><font color="#444444">> ================================================================================== <br></font><font color="#444444">> Vega Lew ( weijia liu) <br></font><font color="#444444">> Graduate student <br>
</font><font color="#444444">> State Key Laboratory of Materials-oriented Chemical Engineering <br></font><font color="#444444">> College of Chemistry and Chemical Engineering <br></font><font color="#444444">> Nanjing University of Technology, 210009, Nanjing, Jiangsu, China <br>
</font><font color="#444444">> ****************************************************************************************************************** <br></font><font color="#444444">> Email: <a href="mailto:vegalew@gmail.com" target="_blank">vegalew@gmail.com</a> <br>
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<br>------ <br>====================================================================== <br>L.F.Huang(黄良锋) ph.D candidate, DFT and phonon physics <br>====================================================================== <br>
Add: Research Laboratory for Computational Materials Sciences, <br>Instutue of Solid State Physics,the Chinese Academy of Sciences, <br>P.O.Box 1129, Hefei 230031, P.R.China <br>Tel: 86-551-5591464-328(office) <br>Fax: 86-551-5591434 <br>
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Vega Lew ( weijia liu)<br>Graduate student<br>State Key Laboratory of Materials-oriented Chemical Engineering<br>College of Chemistry and Chemical Engineering<br>Nanjing University of Technology, 210009, Nanjing, Jiangsu, China<br>
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