[CPMD-list] Energy components in PIMD

[Łukasz Walewski]

Dnia 2008-05-08, czw o godzinie 18:08 +0200, Łukasz Walewski pisze:
> Dnia 2008-04-29, wto o godzinie 07:26 -0400, Axel Kohlmeyer pisze:
> > 
> > dear lukasz,

Dear Axel,

> > can your input conserve energy for a non-PIMD run?
> > ...and then you have to check whether you can maintain
> > adiabacity with the massive thermostat on the ions only.
> > quite a few times, the no-thermostat CP-dynamics is only
> > meta-stable and when you switch to massive N-H chains you
> > excite DOFs that will make the CP dynamics lose it.
> 
> I am trying to understand which DOF you mean - electronic ? ionic ? I
> assume that after 10ps of NVT simulation in 300K those DOF are already
> excited - that's why the dynamics is not adiabatic. Now, what will
> happen if I turned out the termostat on the ions and restart the
> simulation ? If the cause of non-adiabaticity was accidentally inactive
> DOFs then the non-adiabaticity should remain unchanged also in NVE
> simulation. If the restarted NVE run was stable I would assume that the
> cause is different - perhaps connected with the thermostat itself.

I did the above test - I restarted the previous run without the
termostat and got the fictitious kinetic energy drift exactly the same
as it was before the restart
(http://bioexploratorium.pl/ljw/cpmd/nvt/cont.nve/EKINC.png) - first
10ps is the previous NVT run, the remaining ~5ps is the restarted
simulation without the thermostat. It seems that you were right :-)
The rest of the files are in the same directory:
http://bioexploratorium.pl/ljw/cpmd/nvt/cont.nve/

BTW there is a jump in the kinetic energy of the ions
(http://bioexploratorium.pl/ljw/cpmd/nvt/cont.nve/EKIONS.png) that is
incomprehensible for me. It appears in the point of the restart and it
seems to me that some aspect of the previous simulation was not
restarted properly. The input that generated the restart is here:
http://bioexploratorium.pl/ljw/cpmd/nvt/cont.nve/4mdnve.inp and it
differs from the previous NVT one only by those lines:

3c3
<   RESTART WAVEFUNCTION COORDINATES
---
>   RESTART WAVEFUNCTION COORDINATES VELOCITIES NOSEE NOSEP ACCUMULATORS
LATEST
8,11d7
<   TEMPERATURE
<     300.0
<   NOSE IONS MASSIVE
<     300.0  180.8

What did I do wrong with the restart ?

Thanks,
Lukasz