| 10:09:21 PM PST - Mon, Dec 12th 2011 |
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Hi, all.
I have an issue with reproducing data (temperture) in restarting CPMD simulation. I ran the CPMD simulation using PSPW(psedopotential planewave). It is NVE simulation, and I didn’t use any thermostat method. Because I set the number of time steps too less, the simulation was completed before the temperature of the system was equilibrated. So, I restarted program to resume the simulation. To make sure the restart had been correctly done, I checked the .xyz and .energy files- the ones at the last time step in the original simulation and the others at the first time step of restarted simulation. xyz files are exactly same, and kinetic/ potential energies look pretty much same. But there is big discrepancy in temperature: 1230K vs 150K.
I have two questions regarding this restarted simulation. First, what should I do to reproduce the temperature correctly. Is there any command to be added in input file for that? Second, To my knowledge, the temperature is calculated based on the velocities of atoms. In my restarted-simulation, atom velocities were correctly read. So, I’m thinking the temperature also should be same. Would you briefly explain why I got the different temperature in a restarted simulation. As a student, any comments on that would be greatly helpful and appreciated.
I attach the input file for your reference.
geometry units an noautosym noautoz print
# geometry info
end
pspw
simulation_cell
ngrid 32 32 32
end
cutoff 29
ewald_ncut 8
xc xperdew91
dos
mulliken
DPLOT
VECTORS input.movecs
DENSITY total edensity
END
Car-Parrinello
fake_mass 400.0
time_step 5
xc xperdew91
loop 1 2000
xyz_filename traj.xyz
ion_motion_filename ionmotion
emotion_filename energy
EIGMOTION_FILENAME eigenvalues
end
end
set pspw_dplot:iteration_list 1000
task pspw energy
task pspw Car-Parrinello
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