dependence of DFTB-results on the input-sequence of heavy atoms

[X_Hatakeyama]

With respect to the dependence of DFTB-forces on the input-sequence of 
atoms,

I found a new problem that "dependence of DFTB-forces" also depends on the 
input-structure.

For example, when I analyzed dimer of carbon-monoxide (CO),

the dependence of DFTB-forces was changed depending on the distance between 
two CO.

When two CO were separated with a long distance,

only little dependence was obtained.

While, when two CO were contacted, an apparent dependence was obtained.

At last, DFTB-forces of single CO have showed no dependence on the 
input-sequence.

2013年2月13日水曜日 20時36分07秒 UTC+9 X_Hatakeyama:
>
> Dear all,
>
> I'm trying DFTB-calculation of CP2K for molecules consisted of more than 
> three heavy atoms (e.g. CO2).
>
> I have one problem that the atomic-forces depend on the sequence of heavy 
> atoms in the input-file.
>
> For example, the following input coordinates-(A) and (B) showed different 
> results at the calculated forces,
>
> (A),,,{at angstrom-unit}
>
> O  0.0  0.0  +1.2
>
> C  0.0   0.0    0.0
>
> O   0.0  0.0  -1.2
>
> (B),,,
>
> C  0.0  0.0   0.0
>
> O  0.0  0.0  +1.2
>
> O  0.0  0.0  -1.2
>
> Could anyone tell me whether the this problem has been occurred or 
> reported?
>
> To be more precise, the above dependency was not resolved by the following 
> approaches
>
> {Periodicity, SCC-calculation and changing compile condition (e.g. 
> gfortran to ifort within Linux_x86)}.
>
> The only solution was to copy&paste the Slater-Koster file of "co.spl" to 
> "oc.spl",
>
> or to focus on hydrogen compounds (e.g. CH4, H2O, etc.).
>
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