[Pw_forum] Environ-0.2 support Born-Oppenheimer MD ?

Oliviero Andreussi oliviero.andreussi at usi.ch
Tue Jan 26 10:28:55 CET 2016

Dear Chi-Ta,

In the pw.x code the MD engine is indeed Born-Oppenheimer (BO). In the 
cp.x code you also have Car-Parrinello and damped dynamics available. BO 
in pw.x was supported from the very first version of Environ-0.1 and 
from QE-5.1.X. Starting from the new releases of QE (5.3.0) and Environ 
(0.2), the effects of Environ can be used also with the cp.x code and 
with similar results. More info on what is supported and what is not can 
be found on the project/releases webpage 

Please note the following points:
- the implemented environment embedding schemes are not (yet) dynamic, 
in the sense that, at any given time, they are computed on the given 
charge density of the QM system, with no retardation/memory/history 
effects. Thus, the dynamics performed with the continuum dielectric of 
Environ will not have its true meaning, but will provide a sort of more 
statistically averaged dynamics, in which at every step the solvent is 
fully equilibrated with the solute. Whether this suits your applications 
is hard to tell, but for sure it may provide some useful insights (and 
won't cost too much, compared to an explicit solvent simulation).
- the overhead of the Environ calculation with the two codes (pw.x and 
cp.x) is not the same, it is significantly smaller for the BO MD in the 
PW code: the cost of computing the embedding potential is the same in 
the two codes, but the cost of each electronic step is significantly 
different (much smaller in cp.x).

Please let me know if the above answers are not clear enough or if you 
have more doubts.


Oliviero Andreussi

P.S. Please remind to sign with your affiliation, when asking questions 
to this forum.

On 01/25/2016 04:08 PM, Yang, Chi-Ta wrote:
> Dear All,
> Sorry to ask this question. First, I would like to make sure that 
> is MD in PWscf (PW) Born-Oppenheimer MD ? Does Environ-0.2 support 
> this MD?
> Thanks a lot,
> Chi-Ta
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum

Senior Postdoctoral Researcher
École Polytechnique Fédérale de Lausanne (EPFL) and
Università della Svizzera Italiana (USI) of Lugano
USI Campus, Via G. Buffi 17, 6904 Lugano, Switzerland
Emails: oliviero.andreussi @ epfl.ch -or- usi.ch
Tel: +41-(0)58-666-4810 / Skype: olivieroandreussi
Web: https://sites.google.com/site/olivieroandreussi

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