[Pw_forum] Error 254 (fwd)

[Roberto G. A. Veiga]

Axel:
 
thank you.
 
Some questions. Are data related to CG iterations also saved? Where? Where do I find information about the files in the 'outdir' directory? That is, what does each one mean?
 
[]s,
 
Roberto

Axel Kohlmeyer <axel.kohlmeyer at theochem.ruhr-uni-bochum.de> wrote:


resent to pw_forum without attachments, to avoid
spamming everybody's mailbox with 2 megabytes of data,
they (probably) don't need. ;-)

a.

---------- Forwarded message ----------
Date: Fri, 31 Dec 2004 16:51:45 +0100 (CET)
From: Axel Kohlmeyer 
To: Roberto G. A. Veiga 
Subject: Re: [Pw_forum] Error 254


ok, this is one of the 'not-so-obvious to the beginner' type
of problems. you have to be aware, that celldm(...) is in 
_atomic units_ and not in angstrom. when visualizing your
start coordinates _with_ the periodic images, it is obvious,
that you have mixed that up (see the attached snapshots).
if you prefer using angstrom, you can as easily describe
your supercell by:

ibrav = 8, a = 16.0, b = 16.0, c = 5.40224,

and losing the CELL_PARAMETERS section.

[...]
RV> tefield = .false. ,
RV> /
RV> &SYSTEM
RV> ibrav = 0 ,
RV> celldm(1) = 16 ,
RV> nat = 40 ,
RV> ntyp = 2 ,
RV> ecutwfc = 200 ,
RV> ecutrho = 800 ,

wow, you are using a _huge_ plane wave cutoff. what type of
pseudopotentials are you using? if they are norm-conserving
troullier-martins pseudopotentials, you can probably get away
with something between 50 and 100 ry, if they are ultrasoft
pseudopotentials you should get good results with 20-30 ry.

i've attached a set of vanderbilt uspps that should work
very well with ecutwfc = 25.0 and ecutrho = 150.0.

considering the size and the nature of your system, you
should check, whether you need to use more k-points (at least
in z-direction) and/or smearing.

best regards,
axel.

-- 

=======================================================================
Dr. Axel Kohlmeyer e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
Lehrstuhl fuer Theoretische Chemie Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53 Fax: ++49 (0)234/32-14045
D-44780 Bochum http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.

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