# [CP2K-user] Trying to understand the output from neb(band) module

W. Lai wei.... at gmail.com
Sat Nov 14 20:53:41 UTC 2020

```Hi Fabian,

When you said net force earlier I thought you meant sum.  Norm makes

Thanks, Wei

On Saturday, November 14, 2020 at 2:52:46 AM UTC-5 fa... at gmail.com wrote:

> Dear Wei,
>
> The force acting on an atom is a vector. The net force is equal to the
> length of this vector which is computed as the norm, not a simple sum.
>
> Best,
> Fabian
>
> On Saturday, 14 November 2020 at 00:15:01 UTC+1 we... at gmail.com wrote:
>
>> Hi Fabian,
>>
>> Thanks for the clarification.  What you pointed out makes sense.
>> However, I wonder if that was the best way to control convergence.  Let's
>> say your x, y, z forces are 0.1 -0.1 0.001.  The net force will be 0.001.
>> If the max force is set to be 0.002 in the convergence control, this looks
>> fine but we probably shouldn't say the force is converged.
>>
>> Wei
>>
>>
>> On Friday, November 13, 2020 at 2:25:51 AM UTC-5 fa... at gmail.com
>> wrote:
>>
>>> Hi,
>>>
>>> The the force on the first atom of replica Nr. 6 has the components
>>> 0.024362977  -0.000274819  -0.000383546, which results in a net force of
>>> 0.0244. This is precisely what is reported by cp2k.
>>>
>>> Best,
>>> Fabian
>>>
>>> On Friday, 13 November 2020 at 04:27:44 UTC+1 we... at gmail.com wrote:
>>>
>>>> I was playing with the neb tutorial at
>>>> https://www.cp2k.org/exercises:2016_uzh_cmest:path_optimization_neb
>>>> and was using all input files from this site.
>>>>
>>>>
>>>>
>>>> After the second band step, the separate band output gave the following
>>>> convergence check:
>>>>
>>>>
>>>> *******************************************************************************
>>>>
>>>>  RMS DISPLACEMENT =   0.01661     [
>>>> 0.00010]                               ( NO)
>>>>
>>>>  MAX DISPLACEMENT =   0.04582     [
>>>> 0.00020]                               ( NO)
>>>>
>>>>  RMS FORCE        =   0.00459     [
>>>> 0.00500]                               (YES)
>>>>
>>>>  MAX FORCE        =   0.02442     [
>>>> 0.00100]                               ( NO)
>>>>
>>>>
>>>>  *******************************************************************************
>>>>
>>>>
>>>>
>>>> *The screen output has the following energies and force values.  What
>>>> is odd that the max force of all these images is not 0.02442.  Actually
>>>> there is no force that is close to be +-0.0244.  I am wondering what is
>>>> this “MAX FORCE”. Thanks.*
>>>>
>>>>
>>>>
>>>>  NEB| Computing Energies and Forces
>>>>
>>>>  NEB| REPLICA Nr.    1- Energy and Forces
>>>>
>>>>  NEB|                                     Total Energy:
>>>> -14.955972284
>>>>
>>>>  NEB|    ATOM                            X
>>>> Y                Z
>>>>
>>>>  NEB|      C                      -0.000158132     -0.000000000
>>>> -0.000010247
>>>>
>>>>  NEB|      C                       0.000158132      0.000000000
>>>> 0.000010247
>>>>
>>>>  NEB|      H                      -0.000009893     -0.000000000
>>>> 0.000090633
>>>>
>>>>  NEB|      H                      -0.000044050     -0.000068824
>>>> -0.000011886
>>>>
>>>>  NEB|      H                      -0.000044050      0.000068824
>>>> -0.000011886
>>>>
>>>>  NEB|      H                       0.000009893      0.000000000
>>>> -0.000090633
>>>>
>>>>  NEB|      H                       0.000044050      0.000068824
>>>> 0.000011886
>>>>
>>>>  NEB|      H                       0.000044050     -0.000068824
>>>> 0.000011886
>>>>
>>>>  NEB| REPLICA Nr.    2- Energy and Forces
>>>>
>>>>  NEB|                                     Total Energy:
>>>> -14.953424807
>>>>
>>>>  NEB|    ATOM                            X
>>>> Y                Z
>>>>
>>>>  NEB|      C                       0.015511582     -0.000123867
>>>> -0.000363499
>>>>
>>>>  NEB|      C                      -0.015514484      0.000198863
>>>> 0.000377792
>>>>
>>>>  NEB|      H                       0.000857207      0.000192596
>>>> 0.003925016
>>>>
>>>>  NEB|      H                       0.000684401     -0.003902176
>>>> -0.002099542
>>>>
>>>>  NEB|      H                       0.000794070      0.003497209
>>>> -0.002176137
>>>>
>>>>  NEB|      H                      -0.000859132      0.000183216
>>>> -0.003909916
>>>>
>>>>  NEB|      H                      -0.000734015      0.003669315
>>>> 0.002258834
>>>>
>>>>  NEB|      H                      -0.000739709     -0.003761630
>>>> 0.001987922
>>>>
>>>>  NEB| REPLICA Nr.    3- Energy and Forces
>>>>
>>>>  NEB|                                     Total Energy:
>>>> -14.952203598
>>>>
>>>>  NEB|    ATOM                            X
>>>> Y                Z
>>>>
>>>>  NEB|      C                       0.010538684     -0.000238117
>>>> -0.000516915
>>>>
>>>>  NEB|      C                      -0.010542876      0.000214692
>>>> 0.000522403
>>>>
>>>>  NEB|      H                       0.000413313     -0.000291891
>>>> 0.003136219
>>>>
>>>>  NEB|      H                       0.000191793     -0.002982635
>>>> -0.002211249
>>>>
>>>>  NEB|      H                       0.000330883      0.003013668
>>>> -0.001368350
>>>>
>>>>  NEB|      H                      -0.000425288     -0.000291342
>>>> -0.003075548
>>>>
>>>>  NEB|      H                      -0.000246337      0.003274227
>>>> 0.001455731
>>>>
>>>>  NEB|      H                      -0.000260278     -0.002823871
>>>> 0.002056329
>>>>
>>>>  NEB| REPLICA Nr.    4- Energy and Forces
>>>>
>>>>  NEB|                                     Total Energy:
>>>> -14.951836807
>>>>
>>>>  NEB|    ATOM                            X
>>>> Y                Z
>>>>
>>>>  NEB|      C                      -0.000166119     -0.000233856
>>>> -0.000487654
>>>>
>>>>  NEB|      C                       0.000160984      0.000258427
>>>> 0.000483064
>>>>
>>>>  NEB|      H                       0.000029046      0.000183156
>>>> 0.000057179
>>>>
>>>>  NEB|      H                      -0.000172411     -0.000483736
>>>> -0.000359493
>>>>
>>>>  NEB|      H                      -0.000023827      0.000096042
>>>>     -0.000156766
>>>>
>>>>  NEB|      H                      -0.000040779      0.000199584
>>>> 0.000032287
>>>>
>>>>  NEB|      H                       0.000106393      0.000381211
>>>> 0.000225999
>>>>
>>>>  NEB|      H                       0.000106826     -0.000345313
>>>> 0.000203051
>>>>
>>>>  NEB| REPLICA Nr.    5- Energy and Forces
>>>>
>>>>  NEB|                                     Total Energy:
>>>> -14.951407301
>>>>
>>>>  NEB|    ATOM                            X
>>>> Y                Z
>>>>
>>>>  NEB|      C                       0.015874406     -0.000326490
>>>> -0.000555730
>>>>
>>>>  NEB|      C                      -0.015842202      0.000299497
>>>> 0.000559685
>>>>
>>>>  NEB|      H                       0.000535731     -0.002915118
>>>> 0.002845326
>>>>
>>>>  NEB|      H                       0.000312063     -0.001213868
>>>> -0.004546885
>>>>
>>>>  NEB|      H                       0.000505489      0.003928930
>>>> 0.001110436
>>>>
>>>>  NEB|      H                      -0.000585448     -0.002832671
>>>> -0.002713428
>>>>
>>>>  NEB|      H                      -0.000406024      0.004307148
>>>> -0.001105774
>>>>
>>>>  NEB|      H                      -0.000394296     -0.001114621
>>>> 0.004405311
>>>>
>>>>  NEB| REPLICA Nr.    6- Energy and Forces
>>>>
>>>>  NEB|                                     Total Energy:
>>>> -14.952232632
>>>>
>>>>  NEB|    ATOM                            X
>>>> Y                Z
>>>>
>>>>  NEB|      C                       0.024362977     -0.000274819
>>>> -0.000383546
>>>>
>>>>  NEB|      C                      -0.024281416      0.000284322
>>>> 0.000400750
>>>>
>>>>  NEB|      H                       0.001292285     -0.004167767
>>>> 0.002626455
>>>>
>>>>  NEB|      H                       0.001137983     -0.000313475
>>>> -0.005288164
>>>>
>>>>  NEB|      H                       0.001311947      0.004206108
>>>> 0.002313869
>>>>
>>>>  NEB|      H                      -0.001362979     -0.004056262
>>>> -0.002510384
>>>>
>>>>  NEB|      H                      -0.001240025      0.004537593
>>>> -0.002369052
>>>>
>>>>  NEB|      H                      -0.001219620     -0.000261211
>>>> 0.005209053
>>>>
>>>>  NEB| REPLICA Nr.    7- Energy and Forces
>>>>
>>>>  NEB|                                     Total Energy:
>>>> -14.954539124
>>>>
>>>>  NEB|    ATOM                            X
>>>> Y                Z
>>>>
>>>>  NEB|      C                       0.016039728     -0.000166622
>>>> -0.000179795
>>>>
>>>>  NEB|      C                      -0.015936746      0.000181883
>>>> 0.000203661
>>>>
>>>>  NEB|      H                       0.000838326     -0.004015114
>>>> 0.002084504
>>>>
>>>>  NEB|      H                       0.000753054      0.000204003
>>>> -0.004717897
>>>>
>>>>  NEB|      H                       0.000870997      0.003741728
>>>> 0.002384503
>>>>
>>>>  NEB|      H                      -0.000902028     -0.003947288
>>>> -0.002036799
>>>>
>>>>  NEB|      H                      -0.000843340      0.003959916
>>>> -0.002460137
>>>>
>>>>  NEB|      H                      -0.000819474      0.000224363
>>>> 0.004721034
>>>>
>>>>  NEB| REPLICA Nr.    8- Energy and Forces
>>>>
>>>>  NEB|                                     Total Energy:
>>>> -14.955953570
>>>>
>>>>  NEB|    ATOM                            X
>>>> Y                Z
>>>>
>>>>  NEB|      C                      -0.000000797      0.000124456
>>>> 0.000066034
>>>>
>>>>  NEB|      C                       0.000011951     -0.000146750
>>>> -0.000118626
>>>>
>>>>  NEB|      H                       0.000029286      0.000146761
>>>> 0.000101230
>>>>
>>>>  NEB|      H                      -0.000005088     -0.000168487
>>>> -0.000042189
>>>>
>>>>  NEB|      H                       0.000005136      0.000121871
>>>> -0.000047943
>>>>
>>>>  NEB|      H                      -0.000007405     -0.000110873
>>>> -0.000237047
>>>>
>>>>  NEB|      H                      -0.000035252      0.000164078
>>>>  0.000019902
>>>>
>>>>  NEB|      H                      -0.000000769     -0.000171696
>>>> 0.000257590
>>>>
>>>
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