[Pw_forum] Documentation on atomic velocities

[Ilya Ryabinkin]

By the way, to resume an interrupted MD run you DON'T need
ATOMIC_VELOCITIES. They are useful only if you'd like to start (for
whatever reason) with a setup with non-zero *initial* velocities (like
I needed once).

The right way is to use restart_mode = 'restart' with all temporary
files available from the previous (interrupted) step.

The reason is simple: to restart Verlrt algorithm you need more than
initial velocities.


--
I.

On Tue, Mar 21, 2017 at 9:13 PM, Ilya Ryabinkin <igryabinkin at gmail.com> wrote:
> Dear Luis:
> Indeed, there is an undocumented option: pw.x reads the card
> ATOMIC_VELOCITIES once the option
>
> &IONS
>    ion_velocities = 'from_input',
> /
>
> is provided.
>
> They are given in Ry/bohr, no other units are accepted.
>
> --
> Ilya
>
>
> On Tue, Mar 21, 2017 at 6:53 PM, luisen <luisen at metodos.fam.cie.uva.es> wrote:
>>
>> Sorry for not being precise enough. I am using the MD calculation in pw.x
>>
>> Luis E. Gonzalez
>> Univ. de Valladolid
>> Spain.
>>
>>
>> On Tue, 21 Mar 2017, LEUNG Clarence wrote:
>>
>>> Dear Luis,
>>> Do you use the cpmd of cp.x or the md in pw.x?
>>>
>>> Thanks.
>>>
>>> Clarence
>>> City university of Hong Kong
>>>
>>>
>>> -------- Original message --------
>>> From: luisen <luisen at metodos.fam.cie.uva.es>
>>> Date: 21/03/2017 20:42 (GMT+08:00)
>>> To: pw_forum at pwscf.org
>>> Subject: [Pw_forum] Documentation on atomic velocities
>>>
>>>
>>> Dear developers,
>>>
>>> I am interested in using atomic velocities generated in previous MD runs
>>> in order to continue the MD calculation after a finished job (finished
>>> either gracefully or abruptly).
>>> I made a small program to compute the velocities from the positions and
>>> modified slightly the code in order to read the velocities from a file
>>> upon initialization if this file was present. It is however an ad-hoc
>>> solution.
>>>
>>> I have seen in the last distribution (6.1) that there is the possibility
>>> of using a section in the input file named ATOMIC_VELOCITIES.
>>>
>>> My question is if there is any documentation for its use, and if there
>>> is any flag so as to output the velocities (in addition to positions) to
>>> the output file, for later use as input in a subsequent run.
>>>
>>> Yours,
>>>
>>>          Luis Enrique Gonzalez
>>>          Universidad de Valladolid
>>> _______________________________________________
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
>>> http://pwscf.org/mailman/listinfo/pw_forum
>>>
>>
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>
>
>
> --
> *******************************************************
>                     Ilya Ryabinkin
>                  Postdoctoral Scholar
>           Physical and Environmental Sciences
>            University of Toronto Scarborough
>   http://www.utsc.utoronto.ca/~aizmaylov/Members.html
> *******************************************************



-- 
*******************************************************
                    Ilya Ryabinkin
                 Postdoctoral Scholar
          Physical and Environmental Sciences
           University of Toronto Scarborough
  http://www.utsc.utoronto.ca/~aizmaylov/Members.html
*******************************************************