[Pw_forum] Lost in Adiabaticity by using cp.x

[Biswajit Santra]

Hi Sergio,

Is your system metallic or having very small band gap? You may have to do
BOMD. If nothing else works you may use our development version of doing
BMD which uses damped dynamics to optimize wavefunction. It is quite
efficient and cheaper than BOMD in PW, at least for the systems we tested
so far. We plan to put this in QE in the next version. We can send you our
version and you may give us your feedback. Please send us an e-mail if you
wish to try it.

Best wishes,

Biswajit Santra
Mobile: +1-609-227-9202
http://www.princeton.edu/~bsantra/

On Mon, Apr 24, 2017 at 9:04 PM, Sergio Castaneda Ramirez <
scastanr at unal.edu.co> wrote:

> 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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