[Pw_forum] Lost in Adiabaticity by using cp.x

[Sergio Castaneda Ramirez]

Dear users

I'm carrying out a dynamical simulation for a hydroxide ion in a hydrated
segment of a conductive polymer using the cp.x code of Quantum Espresso
V6.1.

This is the general procedure I have been followed: Firstly, I perform an
electronic minimization with fixed ions and cell to reach an electronic
ground state. Secondly, I carry out an ionic relaxation run using damped
molecular dynamics. After that, I add a random displacement of 0.01 a.u. to
take out the ions from equilibrium to perform equilibration (NVT ensemble)
and production (NVE ensemble) runs using verlet algorithm for both
electrons and ions.

However, I haven't be able to keep the adiabaticity of the system when I
perform NVE and NVT simulations. In both cases, kinetic electronic energy
always increases from magnitudes of 1e-6 eV to orders of 0.1-10 after few
time steps, which is totally incorrect. I have tried with different
electronic fictitious masses, time step sizes and pseudopotentials. I also
performed a relaxation of the cell volume using vc-cp, add and thermostat
for the electronic kinectic energy during the NVT runs, but nothing seems
to work. What could you suggest to me to do?

Very thanks in Advance.

Sergio Castaneda
Universidad Nacional de Colombia
Medellin, Colombia
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