[CPMD-list] (no subject)

[Axel Kohlmeyer]

On 10/10/07, kdong_bj at sina.com <kdong_bj at sina.com> wrote:
> Dear every cpmd user,

dear single(!) CPMD user. ;-)

a couple more comments on you post and your problem.

first of all. _please_ don't post to a mailing list in pseudo-html.
use real text mode. for people (like me) that get a lot of e-mail
and thus use a text mode mail program, those are essentially
unreadable, unless i use a graphics mode mailer. ...and the more
effort it is to read an e-mail, the less likely it is to get an answer.

also, always report the version number of CPMD you are using
and platform, compiler, libraries, network etc. as this might play
a role and it takes away a lot of guesswork.

[...]
>
>    My system contains 624 atoms, the DFT is BLYP.
>    but the output file look like as follows,

on top of the recommendation of others, i would stongly
suggest to first try a significantly smaller system. you need
to figure out the optimal parameters anyways, and you get
a much faster turnaround on a smaller (say 100 atom) system.

please also note, that in my experience, you need to choose
more conservative parameters the larger the system.

also, if you have rather little experience in CPMD calculations (which
infer from your not noticing how bad your run turned), i would recommend
to first gain some experience on the technique by trying to redo problems
with published results. to do CP dynamics right needs a bit of a softer
touch than classical MD or gaussian style quantum chemistry calculations.
please keep the TANSTAAFL (= there ain't no such thing as a free lunch)
principle in mind.

[...]

>    Originally, I think the timestep is not correct, but when the timestep is
> increased to 10.0, the NaN ocurred, so I did not know the reasons,
> can you help me?

well, did you consider trying a smaller timestep?


cheers,
    axel.


>
>
>      Best Regards
>     k.dong
>
> 2007-08-28
>  ________________________________
>
> K. dong
> Institute of Process Engineering
> Chinese Academy of Sciences
> P. O. BOX 63, Beijing 100080
> The People's Republic of China
> E-mail: dongkun at home.ipe.ac.cn
>           kdong at foxmail.com
>
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-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
  Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
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If you make something idiot-proof, the universe creates a better idiot.