[QE-users] why internal energy E is circulating around fix temperature in PWscf MD?

[Jayraj Anadani]

Hello, QE community,
I am simulating 128 metallic atoms at 3000K under the NVT ensemble approach
with a velocity-rescaling thermostat in PWscf MD (BOMD-AIMD). After 2.2
picoseconds, I checked some parameters. The temperature, internal energy,
and pressure all equilibrate with time (ps), but when I plot internal
energy (E=F+TS) vs. temperature (K), the energy value circulates around
3000K, which I set.
Is it normal, or am I wrong?
Does this non-zero pressure affect the total energy?
Should I perform vc-relax calculation by fixing the cell volume to
decrease the pressure?

   - find the attached graph at plot.png

[image: plot.png]

Thanks

regards
Jayraj Anadani
SPU Ph.D. Scholar
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