[Pw_forum] About time dependent

Stefano Baroni baroni at sissa.it
Sun May 1 12:17:42 CEST 2011

Dear Mahdi,

not sure I understand what you mean. 

If you apply an external force to a system of atoms, in the Born-Oppenheimer approximation the atoms will move following a classical trajectory, which can be computed using ab-initio molecular dynamics. QE has several options for doing this.

If you want to compute the time-evolution of a system of interacting electrons at clamped nuclei, you can do so using, e.g., time-dependent DFT. I think (but I am not sure and others may confirm or deny ) that the current distribution of QE does contain a code to compute the real-time evolution using TDDFT. I think people from Marzari's group have contributed the code, although I know that other similar codes have been unofficially available for some time now (one was written by Ralph Gebauer).

Finally, if you want to treat on a same footing the quantum dynamics of electrons and the classical dynamics of nuclei, then you should venture in a rather unexplored territory, and I am afraid that no tools are currently available within QE.

Hoper this helps.
Stefano B

On Apr 30, 2011, at 10:27 AM, Mahdi Mirnezhad wrote:

> Dear users,
> Can quantum espresso simulate the time-dependent phenomena? for
> example i want to calculate the position of atoms t second after an
> external force. It is a non-equilibrium phenomena and the total energy
> does not minimum. Is there any way to simulate such phenomena with QE?
> I think in principle we could do such a work. If we have the initial
> position (wave function) the wave function after t simply could be
> written as A0*exp(-ien t), is it correct?
> Best Regards
> Mahdi Mirnezhad
> Guilan University,
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Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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