[CP2K:2236] Re: handling periodic images

[Noam Bernstein]

On Thu, Aug 20, 2009 at 2:58 PM, Teodoro Laino<teodor... at gmail.com> wrote:
>
> Nothing that you are missing Noam.. the only relevant thing is to check
> versus larger values of cutoff.
> If this still does not work could you please send us an input file that
> shows this problem?
> Teo

Hi Teo - the problem still seems to be happening for higher cutoffs
(in the DFT / MGRID section.  Or did you mean some other cutoff?):
original was 280 eV, I've tested up to 500 eV.  It seems to be
associated with a non cubic box.

I've compared finite difference (displacements of 0.001 A) and analytical
forces for atoms # 11 and 12.  Output from my script is below.  As you can
see, atom 11 (0, 1, 2 indicate x,y,z) is always fine.  Atom 12, y component
is bad for all cutoffs.  The problem is definitely there for the 8x8x12 box,
but probably also significant for 8x8x8 box, at least for 500 eV cutoff.

I've attached a tar of the input and output files for the 280 eV cutoff case.
cp2k_input_00.inp is with the unperturbed atoms.
cp2k_input_{11,12}_{0,1,2}_{p,m}.inp are the input files for perturbing atom
11 or 12, along x,y,z (0,1,2) plus (p) or minus (m).

In case you're wondering if atom 11 is just lucky, and the errors I'm seeing
are just the inherent uncertainty (finite convergence, etc), I'm pretty sure
that's not the case: I've also attached a plot of the 280 eV cutoff calculation
perturbing each atom in turn.  Most are fine, but some components of some
atoms are bad. Results appear to be deteministic (to roundoff - I
haven't activated
by deterministic BLACS thing or anything) :)

cutoff_280
11 0 box_8_8_8 f.\hat{dp} 0.0004916814 -(Ep-Em)/|dp| 0.000491293521011838
11 1 box_8_8_8 f.\hat{dp} -0.0066867012 -(Ep-Em)/|dp| -0.00668865940421648
11 2 box_8_8_8 f.\hat{dp} -0.0073745659 -(Ep-Em)/|dp| -0.00737709426227125
12 0 box_8_8_8 f.\hat{dp} -0.0021136905 -(Ep-Em)/|dp| -0.00211417815708393
12 1 box_8_8_8 f.\hat{dp} 0.0055726993 -(Ep-Em)/|dp| 0.00549849856222641
12 2 box_8_8_8 f.\hat{dp} 0.0014391103 -(Ep-Em)/|dp| 0.00143906924693971

11 0 box_8_12_12 f.\hat{dp} -0.0007123294 -(Ep-Em)/|dp| -0.000711781726224949
11 1 box_8_12_12 f.\hat{dp} 0.0002379379 -(Ep-Em)/|dp| 0.000237385293054698
11 2 box_8_12_12 f.\hat{dp} -0.001559587 -(Ep-Em)/|dp| -0.00155971078403945
12 0 box_8_12_12 f.\hat{dp} -0.0029006498 -(Ep-Em)/|dp| -0.00290494006892761
12 1 box_8_12_12 f.\hat{dp} 0.0020685417 -(Ep-Em)/|dp| 0.00141395716560188
12 2 box_8_12_12 f.\hat{dp} -0.0029360325 -(Ep-Em)/|dp| -0.00293513967970238

cutoff_400
11 0 box_8_8_8 f.\hat{dp} 0.0004532311 -(Ep-Em)/|dp| 0.000452920517698878
11 1 box_8_8_8 f.\hat{dp} -0.0065719708 -(Ep-Em)/|dp| -0.00657400259956961
11 2 box_8_8_8 f.\hat{dp} -0.0072055205 -(Ep-Em)/|dp| -0.00720823932810143
12 0 box_8_8_8 f.\hat{dp} -0.0016856163 -(Ep-Em)/|dp| -0.00168413189450205
12 1 box_8_8_8 f.\hat{dp} 0.0041391955 -(Ep-Em)/|dp| 0.00441285014032413
12 2 box_8_8_8 f.\hat{dp} -0.0011994313 -(Ep-Em)/|dp| -0.00119672725088764

11 0 box_8_12_12 f.\hat{dp} -0.0007816439 -(Ep-Em)/|dp| -0.000781034905513324
11 1 box_8_12_12 f.\hat{dp} -7.26663e-05 -(Ep-Em)/|dp| -7.30428596077753e-05
11 2 box_8_12_12 f.\hat{dp} -0.0018072394 -(Ep-Em)/|dp| -0.00180724910219993
12 0 box_8_12_12 f.\hat{dp} -0.0023819861 -(Ep-Em)/|dp| -0.00238044322314767
12 1 box_8_12_12 f.\hat{dp} -0.0010494 -(Ep-Em)/|dp| -0.000692416029119044
12 2 box_8_12_12 f.\hat{dp} -0.0052477217 -(Ep-Em)/|dp| -0.00524389075836397

cutoff_500
11 0 box_8_8_8 f.\hat{dp} 0.0004411373 -(Ep-Em)/|dp| 0.00044082063995588
11 1 box_8_8_8 f.\hat{dp} -0.0065601726 -(Ep-Em)/|dp| -0.00656222765598964
11 2 box_8_8_8 f.\hat{dp} -0.007251686 -(Ep-Em)/|dp| -0.00725439636545722
12 0 box_8_8_8 f.\hat{dp} 0.0005936416 -(Ep-Em)/|dp| 0.000592566653785405
12 1 box_8_8_8 f.\hat{dp} 0.0065679237 -(Ep-Em)/|dp| 0.00494262781109822
12 2 box_8_8_8 f.\hat{dp} 0.0016459685 -(Ep-Em)/|dp| 0.00164566239381169

11 0 box_8_12_12 f.\hat{dp} -0.0008026305 -(Ep-Em)/|dp| -0.000802018700904088
11 1 box_8_12_12 f.\hat{dp} -6.38405e-05 -(Ep-Em)/|dp| -6.42142294224967e-05
11 2 box_8_12_12 f.\hat{dp} -0.0018938615 -(Ep-Em)/|dp| -0.00189382499706237
12 0 box_8_12_12 f.\hat{dp} -7.53328e-05 -(Ep-Em)/|dp| -7.63967225168129e-05
12 1 box_8_12_12 f.\hat{dp} 0.001442685 -(Ep-Em)/|dp| -0.000163606731184927
12 2 box_8_12_12 f.\hat{dp} -0.002501446 -(Ep-Em)/|dp| -0.00250087689833935
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