[Pw_forum] MD with manual velocities and printing of updated velocities

[Paolo Giannozzi]

Currently it is not possible to provide atomic velocities from input in
pw.x. It can be done with the Car-Parrinello code.

Velocities are not used in the Verlet algorithm implemented in pw.x. They
have to be computed from positions as (x(t+dt)-x(t-dt))/(2dt)

Paolo

On Mon, Oct 19, 2015 at 6:16 PM, Venkataramana Imandi <
venkataramana.imandi at gmail.com> wrote:

>
> Dear QE users,
>
> I checked entire manual and keywords list of pw.x, there is nowhere
> information about manual entering of atomic velocities in the input file,
> If necessary sometimes. Moreover, I have seen dynamics_module.f90 file, it
> is shown that velocities are initialized from Maxwell-Boltzmann
> distribution or random number distribution or zero velocities. So, please
> make me understand,
> how to give manually velocities at a particular time step. In the input
> file, I am giving atomic coordinates in the angstrom units. If there is an
> option to give velocities in the input file, please
> tell me keywords information and what type of units I have to give for
> velocities (e.g. angstroms/rydberg, Bohrs/rydberg).
>
> In addition, in the output file, there is only updated atomic coordinates
> and no updated velocities at each time step. Can you please give a comment
> of the bit of code along with where to insert those bit of code in the
> dynamics_module.f90 file or wherever in the code, by that I can improve to
> add or doing something on the code to print updated velocities at each time
> step. Please, any suggestions are necessary to me. I don't have much
> command on the code, at-least I can try my level best.
>
> I anticipated thanks for suitable answers from well-wishers.
>
>
> venkataramana
> PhD student
> IIT Bombay
>
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>



-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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