Bug? The conserved quantity is NOT conserved after flexible cell MD is restarted

Rustam rusta... at gmail.com
Sat Aug 13 07:56:39 CEST 2016


Hi guys,

As Amandine Chouanard mentioned in a recent post  
<https://groups.google.com/forum/#!topic/cp2k/mwieBkpEjns>the conserved 
quantity shows discontinuities when a flexible cell MD simulation is 
restarted. I used her input file and found that restart works fine with NVT 
and NPT_I simulations, but NOT with NPT_F (see attached figure). The 
discontinuities in NVT_F the conserved quantity are larger if restarts are 
less frequent (i.e. trajectory pieces are longer).

It seems that the conserved quantities in NPT_I and NPT_F simulations are 
computed by the same subroutine in motion/md_conserved_quantities.F:390. So 
it seems that the restart file contains ALL data on the current state of 
the barostat and thermostat to ensure a smooth restart.

Is it possible that this has something to do with the CELL_REF setting? 
Something along the lines that the grids before and after the restart are 
different? I tried printing the GRID info but it seems to keep the number 
of points constant...

I will appreciate any suggestions/comments,
Rustam


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