# Why some overlapped steps appear in the new trajectory file after RESTART the MD in the CP2K?

jia huangji... at gmail.com
Tue Dec 11 12:33:47 UTC 2012

```Hello Everyone,
When I calculate the MD with CP2K.  Some overlapped steps appear in the
new trajectory file after RESTART the MD.
For example, I already get the MD output of  i=3906,
...

773
i =     3906, time =     1953.000, E =     -4474.7541142663
N        18.9864963170        8.7518562091       10.6256224398
O        18.5387553608        9.8006093920       11.1299284364
O        18.3563092587        7.6487763074       10.7699162566
O        20.0918231195        8.7474007752        9.9520189788
---
H        11.0477142399       10.5711430820       17.8516880476
H        10.3012118921        9.3683700815       18.6096133300

So when we restart the MD again, I expect that  the 3907th step will come
out. But the result is 3901st step, 3902nd steps, 3903rd steps,.... then I
have two  3901st,3902nd,..., 3906th step. Unfortunately, the data is
different between the two "3901th step" trojectory (for, 3902nd,
3903rd,...,3906th step as well).

773
i =     3901, time =     1950.500, E =     -4474.7861914555
N        18.9915342896        8.7315755847       10.6140689267
O        18.5431556496        9.7796178151       11.1373780816
O        18.3407752730        7.6450796766       10.7633629707
O        20.1093185435        8.7631643653        9.9548188259
...

773
i =     3902, time =     1951.000, E =     -4474.7782316820
N        18.9900734976        8.7359794467       10.6165886903
O        18.5428202911        9.7832959747       11.1359394674
O        18.3441426920        7.6460054209       10.7644822741
O        20.1059971546        8.7607514539        9.9543488296
...

...

Since there is a jump  between the energy (position) of the 3906th step in
the last MD trajectory and  the energy (position) in the 3901st step in the
current one, some calculation, such as time correlation function,  will be
not accurate. So it is better to solve this problem.  Does anyone know the
possible reasons for this overlapped trajectory?  Thanks a lot advanced.

Jia

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