[DFTB-Plus-User] MD in liquid water

[Ben Hourahine]

Hello Paulo,

the problem seems to be set of by the nitrogen atoms in the
input. Your structure doesn't actually have any N atoms, but there are
several places where there are settings for these, which when commented
out/removed should cure the problem:

TypeNames = {"O" "H" "C"}# "N"}

#    N-H = "N-H.skf"
#    H-N = "H-N.skf"
#    C-N = "C-N.skf"
#    N-C = "C-N.skf"
#    N-N = "N-N.skf"
#    O-N = "O-N.skf"
#    N-O = "O-N.skf"

#    N = "p"

it looks like you have found a bug in the parsing of the input in
this case.

Regards

Ben

Paulo Cesar Piquini wrote:
> Dear Mark,
> 
> attached you will see the input and the output files of one of my tests.
> I played with some variables as timestep and others but the result was
> similar or worst.
> As you will see, the SCC cycle does not achieve convergence. If one
> increases the number of iterations, it goes well until some cycle and
> then the problem appears again.
> Thanks
> 
> Yours
> Paulo
> 
> On Tue, Oct 6, 2009 at 12:19 PM, Christopher Mark Maupin
> <cmaupin at hec.utah.edu <mailto:cmaupin at hec.utah.edu>> wrote:
> 
>     DEar Paulo Cesar Piquini,
>      I have conducted several liquid water simulations and have not seen
>     this issue.  Can you please attach your input file and the output file.
> 
>     Best wishes,
> 
>     Mark
> 
>     Paulo Cesar Piquini wrote:
>     > Dear users of DFTB+
>     >
>     > I am a new user of DFTB+ and Iam having difficulties to make the SCC
>     > cycle to converge when I simulate a liquid water at 300 K.
>     > Have someone already performed similar calculations successfully?
>     >
>     > Thanks
>     > Paulo Piquini
>     >
>     > --
>     > Paulo Cesar Piquini
>     > Departamento de Física
>     > Universidade Federal de Santa Maria
>     > 97105-900
>     > Santa Maria, RS
>     > Brasil
>     > Fax: 55 55 3220-8032
>     > e-mail: ppiquini at gmail.com <mailto:ppiquini at gmail.com>
>     <mailto:ppiquini at gmail.com <mailto:ppiquini at gmail.com>>;
>     > ppiquini at smail.ufsm.br <mailto:ppiquini at smail.ufsm.br>
>     <mailto:ppiquini at smail.ufsm.br <mailto:ppiquini at smail.ufsm.br>>
>     > http://w3.ufsm.br/piquini
>     >
>     >
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> 
> 
> 
> -- 
> Paulo Cesar Piquini
> Departamento de Física
> Universidade Federal de Santa Maria
> 97105-900
> Santa Maria, RS
> Brasil
> Fax: 55 55 3220-8032
> e-mail: ppiquini at gmail.com <mailto:ppiquini at gmail.com>;
> ppiquini at smail.ufsm.br <mailto:ppiquini at smail.ufsm.br>
> http://w3.ufsm.br/piquini
> 

-- 
     Dr. B. Hourahine, SUPA, Department of Physics,
   University of Strathclyde, John Anderson Building,
          107 Rottenrow, Glasgow G4 0NG, UK.
    +44 141 548 2325, benjamin.hourahine at strath.ac.uk
   The University of Strathclyde is a charitable body,
registered in Scotland, with registration number SC015263