Resuming NVT QMD simulation from last step completed


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Hi!

I'm new to using NWChem. I recently ran some NVT QMD calculations that need to be restarted (using last step of previous run, so the same trajectory). I thought it would be enough to put the xyz coordinates and velocities from the *qmdrst file into the new *.nw file, but for some reason when I do that, the calculation doesn't converge. For example,

N 2.325039669782 -4.339549242302 -2.706314214255 -0.000014966578 -0.000007262146 -0.000149389862
N 0.147407844631 -4.805721439464 -2.021316232823 0.000185610278 0.000148404783 -0.000244449396
C 3.532833497234 -1.873740795215 -2.543584099107 -0.000320032905 0.000176611789 0.000190434506
C -1.270775090625 -3.048081654924 -0.567471814594 -0.000255831618 0.000070917945 -0.000267568364
C 6.126241119878 -1.877937964085 -2.064133205631 -0.000275644614 0.000260448086 0.000030549312
C -3.788675415701 -2.470920500398 -1.227672316593 0.000240561272 0.000027013465 -0.000060437809
C 2.162097699578 0.350250257851 -2.947916772779 -0.000075080709 -0.000115839267 -0.000108453838
C -0.118290022081 -2.075276724678 1.663050021308 0.000222882485 0.000249557999 -0.000035755846
C 7.379659872152 0.410248660906 -1.858004782923 -0.000185804657 -0.000004253468 -0.000066680495
C -4.992319852420 -0.620055251543 0.206701237735 -0.000153604718 0.000040080594 0.000368634591
C 3.564282686086 2.646027095979 -2.975617151176 0.000116126658 -0.000180113433 -0.000216705394
C -1.360770823390 -0.326099186961 3.101414972184 0.000083904937 -0.000273886827 0.000280957937
C 6.093574003681 2.596444122901 -2.462574394581 0.000201955945 0.000037866120 0.000067064590
C -3.783977185890 0.469255453865 2.281699730268 0.000582860910 -0.000148615308 -0.000254081187
H 7.191331155731 -3.632680781813 -1.875065194235 -0.000204768143 0.000999891219 -0.000598912167
H -4.505517383868 -3.420686046372 -2.861470801187 0.000388841260 -0.000948036262 0.000183537662
H 0.023951818411 0.417722122074 -2.917603735196 0.000086350542 -0.000066272273 -0.001117245375
H 1.773721255024 -2.729727758607 1.973029481898 -0.000179234062 0.000900907583 0.000789181230
H 9.387481782378 0.467184651948 -1.484331407320 0.000217674543 0.000100387242 0.000447378582
H -7.027487418769 -0.050077691818 -0.204927156964 0.000860992558 0.000099564645 -0.000136834775
H 2.655207324319 4.524094737090 -3.159053137063 0.000872191243 -0.000253297034 0.000073217624
H -0.298795591404 0.492547154161 4.749930509900 0.000730793613 0.000611790625 -0.000442684901
H 7.048254916653 4.454109596707 -2.364309518306 0.000967671694 -0.000807110141 -0.000275367373
C -4.271697858169 3.005069810071 3.606195946875 -0.000079499434 -0.000023206610 0.000237283045
O -2.453043565609 4.148905627446 4.383062676801 0.000023539575 -0.000061271881 0.000114792993 \
       mass 50.397
O -6.716196038485 3.924288500124 3.914443532602 0.000292784997 -0.000077889303 0.000002800994 \
       mass 50.397
H -6.387817717372 5.517835520235 4.865828235209 0.000392859208 -0.001669512572 -0.000884351216
end

is the geometry in the *.nw file. Below is from the output:

Requested integration accuracy: 0.10E-05
d= 0,ls=0.5,diis    20   -702.2483681310 -3.72D+00  2.15D-03  1.16D+02    43.6
Grid integrated density: 118.000137491527
Requested integration accuracy: 0.10E-05
d= 0,ls=0.5,diis 21 -704.6195721562 -2.37D+00 6.30D-02 1.08D+02 45.5
Grid integrated density: 118.000165745459
Requested integration accuracy: 0.10E-05
d= 0,ls=0.5,diis 22 -481.3720552044 2.23D+02 5.44D-02 2.59D+02 47.4
d= 0,ls=0.5,diis 23 -653.9106108183 -1.73D+02 4.44D-02 1.47D+02 49.3
d= 0,ls=0.5,diis 24 -638.8409623240 1.51D+01 4.06D-02 1.56D+02 51.2
d= 0,ls=0.5,diis 25 -732.3370631607 -9.35D+01 1.43D-02 7.15D+01 53.0
d= 0,ls=0.5,diis 26 -739.3412209373 -7.00D+00 9.91D-03 4.64D+01 54.5
d= 0,ls=0.5,diis 27 -747.8053729068 -8.46D+00 1.42D-02 2.53D+01 56.4
d= 0,ls=0.5,diis 28 -744.8307885840 2.97D+00 4.23D-03 4.14D+01 58.3
d= 0,ls=0.5,diis 29 -746.1088868623 -1.28D+00 3.00D-03 3.26D+01 60.2
d= 0,ls=0.5,diis 30 -747.3614086787 -1.25D+00 3.36D-03 3.03D+01 62.2

     Calculation failed to converge
------------------------------

And then at the end of the file:

For further details see manual section:
This type of error is most commonly associated with calculations not reaching convergence criteria
------------------------------------------------------------------------
For more information see the NWChem manual at http://nwchemgit.github.io/index.php/NWChem_Documentation


For further details see manual section:
7:qmd_gradient: task_gradient:Received an Error in Communication
13:qmd_gradient: task_gradient:Received an Error in Communication
1:qmd_gradient: task_gradient:Received an Error in Communication
3:qmd_gradient: task_gradient:Received an Error in Communication
9:qmd_gradient: task_gradient:Received an Error in Communication
10:qmd_gradient: task_gradient:Received an Error in Communication
11:qmd_gradient: task_gradient:Received an Error in Communication
14:qmd_gradient: task_gradient:Received an Error in Communication
[i31:154004] 1 more process has sent help message help-mpi-api.txt / mpi-abort
[i31:154004] Set MCA parameter "orte_base_help_aggregate" to 0 to see all help / error messages
                                                                                                  

Any help is appreciated. Also, sorry for the poor formatting!

Forum Regular
To restart your trajectory, you just need to have your restart file (*.qmdrst) in the working directory. The code checks for the presence of that file, and if it exists, it uses the information in the file to initialize the calculation as far as atomic positions, atomic velocities, and current step number are concerned.

So, for example, if you want to extend a trajectory, you just need to change the nstep_nucl value in the input file to the desired total number of steps and rerun the calculation (you can also modify your input to have it reread the last set of molecular orbitals generated to use as the initial guess, but this is not required).

Unfortunately, with NWChem v6.6, the QMD code does not actually look in the input file for atomic velocities (that was an oversight on my part), so the method you tried would not work. However, v6.8 does have this functionality (http://nwchemgit.github.io/Special_AWCforum/st/id2459/Second_release_candidate_for...)

Clicked A Few Times
Thank you!


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