[Pw_forum] Re:Re:vc-relax (Eric Abel)

Eric Abel etabel at hotmail.com
Tue Sep 12 18:17:10 CEST 2006

Thank you all for your tips.  It turns out the real fix was to upgrade to 
the latest stable version.  Now the program is behaving as I would expect.

Cesar, you mention the parameters wmass and dt...I was wondering if there is 
a way to get an initial estimate for these values.  Unfortunately the 
documentation on this is sketchy at best.

Right now I am running with wmass=0.1, and I didn't set dt, so it must be 
using the default.  Things are converging slowly...the atomic forces are 
creeping down.


>From: cesards at msi.umn.edu
>Reply-To: pw_forum at pwscf.org
>To: pw_forum at pwscf.org
>Subject: [Pw_forum] Re:Re:vc-relax (Eric Abel)
>Date: Mon, 11 Sep 2006 20:37:18 -0500 (CDT)
>Hi Eric,
>It is OK, I understand your problem now: Your damped dynamics cicle heve
>NOT converged. If dt parameter in &CONTROL, wmass in  &CELL namelist and
>atomic masses are not set properly damped wc-dynamics takes too long to
>converge. If you are not running in damped mode, the keywords tosearch are
>"new lattice vectors (alat unit) :" and "new positions in cryst coord".
>The program will report those at end of every MD step.
>Also remember to set nstep in &CONTROL namelist to an appropriate number,
>depending on the numbers of degrees of freedom, and the fine tunning of
>paremeters above.
>If you want to learn how to optimize dt, wmass and atomic masses, take a
>look at the several tutorials at
>Cesar R.S. da Silva.
>Pw_forum mailing list
>Pw_forum at pwscf.org

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