[Pw_forum] temperature oscillations with nose' thermostat

[Massimiliano Bonomi]

  Dear users,
I'm running molecular dynamics with fpmd (in espresso v. 2.1.3 package) 
of a solid assembled with cluster of gold.
After reaching the electronic ground state i've started the dynamics 
using nose' thermostat
both on ions and electron, choosing the right thermostat frequencies 
(for ions half the higher phonon frequency, for electrons 2/3 times the 
higher phonon frequency).

During a simulation of 10000 time step (~ 1.0 picoseconds) at T=300K  
the temperature of the system  made big oscillations around 300K (even 
of 200K!!).

Is it normal?? How can i reduce the width of these oscillations?

Best regards and thanks in advance.
Massimiliano Bonomi.

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Massimiliano Bonomi
Dipartimento di Fisica, Università degli Studi di Milano  
via Celoria, 16 - 20133 Milano, Italy
ph. +39 02 50317 717
e-mail: massimiliano.bonomi at mi.infn.it, massimiliano.bonomi at unimi.it