[Q-e-developers] lost control of the temperature in MD

[Kun Wang]

Hi,
      We cannot control the temperature when I use the "nose" thermostat (fnosep has been decreased to 10) to simulate dehydrogenation in my system as the details below. The temperature in the simulation appears a very large fluctuation from 100K to 1200K where actually what we set is only 373K.
      We have performed these steps (following the Quantum Espresso tutorial: Car-Parrinello Molecular Dynamics) (see the input and output files attached).
http://www.fisica.uniud.it/~giannozz/QE-Tutorial/tutorial_cp.html

1) optimized the geometry of  Mg(BH4)2(NH3)2 using CASTEP
2) found the ground state (AMgB-wav4.evp)
3) randomized atoms positions: all atoms in the unit cell were displaced by 0.01 bohr, 50 steps (AMgB-random.evp)
4) MD: initialized both the electronic and ionic velocities to 0, 5000 steps (AMgB-md1.evp)
5) MD: removed the quench of electronic and ionic velocities, 5000 steps (AMgB-md2.evp)
6) MD: restarted the trajectory with a Nose-Hoover thermostat, 373K, 5000 steps (AMgB-md3.evp, AMgB-md3.in)

So could you please help to give us some advises? Where is our problem?
Thank you very much!
Best wishes
KUN

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