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[lan haiping <lanhaiping@gmail.com>]

Hi,

1.0 d-3 is really too large to accept for abinit calculation, since the unit for tolmxf is Ha/a.u rather than eV/Ang.

On Wed, Apr 29, 2009 at 9:54 PM, Ludwig, Christian <ludwigc@uni-mainz.de> wrote:

I am using 1.0d-3 for tolmxf. I found this value in published papers, so I figured it should be enough for my case.
In principle I agree, of course one should relax the forces, but in my case it took 74 Broyden steps for convergence. And the forces did not converge nicely. I had the impression that the fluctuate pretty randomly between 1.0d-2 and 1.0d-3 until incidentally there are two consecutive low values. The development of the forces does not look systematic.
________________________________________
Von: Josef Zwanziger [jzwanzig@gmail.com]
Gesendet: Mittwoch, 29. April 2009 15:32
An: forum@abinit.org
Betreff: Re: [abinit-forum] alternative to tolmxf

Dear Christian,

what would it mean to relax a structure without relaxing the forces?
What value of tolmxf are you using? If you really don't care about
getting a highly accurate structure, you could simply set tolmxf to a
coarse value (1.0D-4 say).

On Wed, Apr 29, 2009 at 10:13 AM,  <ludwigc@uni-mainz.de> wrote:
> I am trying to relax a structure and observe the following: while the total
> energy is stable pretty quickly, the forces fluctuate for some time, which
> prevents a quick convergence. Since the total energy is the only value I am
> interested in, it would be nice to set a convergence criterion analogous to
> toldfe for the Broyden steps. Is this somehow possible? I found nothing in the
> list of input variables.
>
> Christian
>



--
Josef W. Zwanziger
Professor of Chemistry
Canada Research Chair in NMR Studies of Materials
Director, Atlantic Region Magnetic Resonance Centre
Dalhousie University
Halifax, NS B3H 4J3 Canada
tel: +1 (902) 494-1960
fax: +1 (902) 494-1867
web: http://jwz.chem.dal.ca
jzwanzig@gmail.com, jzwanzig@dal.ca

-- 
Hai-Ping Lan 
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping@gmail.com, hplan@pku.edu.cn