[CPMD-list] temperature Drift in CPMD

[Ho]

Dear CPMD users:

I am performing a NVE CPMD simulation on a system with 105 atoms (35 O, 65
H, 3 F, 1C, 1 S). The system was initially equilibrated using NVT for about
30 ps and then switched to NVE for another 30 ps. While the potential energy
(Eks) and the kinetic energy of ions (Temp) fluctuated around some mean
value, I observed a constant increase of electron kinetic energy (Ekinc) at
a rate of 0.0003 Hartree/ps. 

Can I safely ignore this and take the systems equilibrated? Or do I need to
take other measures  to ensure the equilibration of the system? I have in
fact tried to quench the electron (QUENCH BOELECTRON) after the NVE
simulation but then found that the system temperature drops. Is there a
better way to equilibrate the system? Following
is the detailed procedure that I used in my simulation. Any
comments/suggestions are greatly appreciated.


Here's the simulation procedure. Initially I set 

TEMPCONTROL IONS 
400.0 80.0 
TIMESTEP
  5.0
and did about 1.5 ps simulation. Then I shifted whole systems to my desired
temperature 

QUENCH BOELECTRON
TEMPERATURE
   353.0
 TEMPCONTROL IONS
   353.0 70.0
TIMESTEP
  5.0
for about 4.8ps simulations.  I observed the Ekinc is oscillated around
0.013. I use the
value and shifted the system to NOSE NVT simulation and set
 
QUENCH BOELECTRON
NOSE IONS
     353.0d0   3000.0d0
 NOSE ELECTRONS
    0.0125d0  10000.0d0
TIMESTEP
  5.0
for 12ps. Then I shifted the system into NOSE ION MASSIVE for about 12ps.
Later I released whole temperature control and tried to do a NVE simulation.
During a 30 ps simulation, I observed the TEMPP and EKS could maintain at a
mean value, but Ekinc
increased about 0.008 with a constant slope. 




Thanks and Regards

Ying-Chieh Hung