The ABINIT Users Mailing List ( CLOSED )

[Masayoshi Mikami <mmikami@yk.rim.or.jp>]

Hi everyone, 
A Happy ("Abinit") New Year ! (*)

This Q&A is already included :
http://www.abinit.org/ABINIT/Infos/FAQ.htm#scfcge
Another way might work ... (kindly click #2 as well)
If other tips would be available, could you let us know ?

Just one commnet:
I guess that this may also be related to the geometry 
where the SCF fails... As a last resort, the geometry 
may be a bit "relaxed" by "guessing", e.g. inward ... 
(It should need some experience ... In fact, I did such
"manual relaxation" for initial geometries for some surfaces)
I guess that there might be theoretical works related 
to such diamond surfaces, which may be helpful before 
starting calculations ... Have you tried literature survey ?
e.g. Some WEB sites such as www.ingenta.com may help.

Recently I have updated the FAQ, which will be available 
on the ABINIT WEB/src_tests_*.tar.gz after it is checked ... 

Best wishes,
Masayoshi

P.S. (*) A few years ago, Gilles made this wording. ;-)

From: verstraete@pcpm.ucl.ac.be
Subject: Re: [abinit-forum] convergence problem
Date: Mon, 5 Jan 2004 12:42:18 +0100 (CET)
Message-ID: <Pine.LNX.4.58.0401051235350.28862@spectro>

> 
> The problem has already been raised several times in the forum (check the
> archives). Mikami-san, could you put something on the FAQ, please?
> 
> The default CG line-minimization algorithm restarts if it finds a bad
> curvature for the energy around its starting point. If it restarts 13
> times (bad or slow convergence) the program stops. The 13 is arbitrary,
> but indicates the problem is difficult (Xavier: perhaps an input variable 
> to keep abinit from exiting because of this?).
> 
> Solution:
> --------
> Use iscf 3 (anderson mixing). It is slower but more robust, and never 
> gives the "13 restart" error. I use it systematically without any 
> difficulties or very noticeable slowdown w.r.t. iscf 5 (default).
> 
> cheers and happy gnu year.
> 
> Matthieu
> 
> 
> On Mon, 5 Jan 2004, xianghjun wrote:
> 
> > I also have the same problem and wish somebody to help us.
> > Best Regards
> > xianghjun
> > sefa dag wrote:
> > 
> > >
> > >  Dear Sir/Madam,
> > >
> > >    I have a convergence problem. Just I am trying to do test 
> > > calculations with  ABINIT program.
> > > I want to look at the surface phonons on the C(100) surface. For this 
> > > reason I am using  "t56.in" (from Tutorial)
> > > input file  as template. I am using Troullier-Martins pseudopotential 
> > > for C.
> > > When I run abinit program, program stops and it gave this error message:
> > >
> > > scfcge : ERROR -
> > >  Potential-based CG line minimization not converged after 13 restarts.
> > >  Action : read the eventual warnings about lack of convergence.
> > >  Some might be relevant. Otherwise, raise nband.
> > >
> > > leave_new : decision taken to exit ...
> > >
> > > I could not understand this. I increased number of bands. But it gave 
> > > the same result. Also I am using enaugh number of k-points.
> > > In the output file convergence
> > > of energy seems okey
> > > ...
> > > ...
> > > ...
> > > ETOT 36  -71.813161986653     5.761E-09 1.618E-08 9.264E-02 9.874E-06 
> > > 2.604E-02
> > > ETOT 37  -71.813161982648     4.006E-09 6.845E-09 8.051E-02 5.358E-06 
> > > 2.603E-02
> > > ETOT 38  -71.813161980057     2.591E-09 2.972E-09 7.442E-02 3.124E-06 
> > > 2.603E-02
> > > ETOT 39  -71.813161978387     1.669E-09 1.319E-09 7.091E-02 1.917E-06 
> > > 2.603E-02
> > > ETOT 40  -71.813161977299     1.088E-09 5.976E-10 6.872E-02 1.220E-06 
> > > 2.603E-02
> > > ETOT 41  -71.813161976579     7.207E-10 2.753E-10 6.730E-02 7.978E-07 
> > > 2.603E-02
> > > ETOT 42  -71.813161976095     4.834E-10 1.281E-10 6.635E-02 5.321E-07 
> > > 2.603E-02
> > > ETOT 43  -71.813161975767     3.280E-10 5.974E-11 6.571E-02 3.599E-07 
> > > 2.603E-02
> > > ETOT 44  -71.813161975543     2.244E-10 3.026E-11 6.527E-02 2.459E-07 
> > > 2.603E-02
> > > ETOT 45  -71.813161975388     1.544E-10 1.506E-11 6.496E-02 1.692E-07 
> > > 2.603E-02
> > > ETOT 46  -71.813161975281     1.078E-10 7.314E-12 6.475E-02 1.170E-07 
> > > 2.603E-02
> > > ETOT 47  -71.813161975206     7.419E-11 3.475E-12 6.461E-02 8.123E-08 
> > > 2.603E-02
> > >
> > > why it can not stop to do self-consistent calculation?
> > >
> > > In the input file there is tolvrs parameter. Tutorial says this must 
> > > be between  e-18 and e-22.
> > > i am taking:
> > > tolvrs1   1.0d-18       # SCF stopping criterion
> > > I also used toldfe parameter instead of this. It also gave the same 
> > > error.
> > >
> > > What can I do about it? Could you please help me about it?
> > >
> > > Thank You
> > >
> > >
> > 
> > 
> > 
> 
> -- 
> ===================================================================
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> 
> Matthieu Verstraete               mailto:verstraete@pcpm.ucl.ac.be 
> PCPM, Boltzmann, pl. Croix du Sud, 1            tel: 010/ 47 33 59
> B-1348 Louvain-la-Neuve  Belgium                fax: 010/ 47 34 52