[CP2K:3675] Re: All electron calculations

[Eva Pluharova]

Dear Marcella,

thanks for help and quick reply. Originally, I started with default
values of EPSFIT, EPSISO, EPSRHO0, but since I was getting strange
electron density, which I will write about in the next paragraph, I
changed them, because I though it would make convergence tighter...
But I made things much worse. I use higher cutoff, because I am
planning to add cations, for which it is necessary and I want to have
the same set up for everything.

Going back to default values solves the problems 1. and 2., but not
the third one. One part of it is incorrect normalization of total
electron density, which prevents me from running Bader population
analysis, second part are artifacts that you can see in attached
snaphots.

There are two snapshots of water molecule with total electron density
plotted at isovalue 1000 and 4000 (whatever this means...). There are
small blobs completely outside the area of the molecule. Even more
interesting is CH3CONHCH3 abbreviated as NMA, the same artifacts
appear on the methyl group, methyl C, H, H are the first atoms in the
coordinate file NMA-pos.xyz. If I place carbonyl atoms C and O and N
to the first three places in coordinate file  NMA-pos-perm.xyz,
artifacts appear on these 3 atoms.

Do you have any suggestion how to solve this? Thank you very much.
Best regards,
Eva


2011/12/14 marci <marc... at pci.uzh.ch>:
> Dear Eva
>
> according to your input, you changed the values of some parameters
> (EPSFIT, EPSISO, EPSRHO0) related to the construction of the local
> densities
> for all electron calculations.
> Why?
> The result is that the local densities are not accurately described.
>
> As a general rule, if you do not know what a parameter is really
> doing,
> better to trust the default values that are typically reasonable in
> cp2k.
>
> With your input and the default EPS... parameters I get the following
> Mulliken charges
>     1  O   -0.75837
>     2  H    0.379019
>     3  H    0.379019
>
> I would like to add that it is not true that you need a higher cutoff
> for all-electron calculations with the GAPW method.
> In normal cases 250 Ry are sufficient,  because the hard part of the
> density is not "collocated" on the PW grid.
> However, when printing the total density to a cube file (only then),
> the whole density is "collocated" on the grid, and
> this is most probably not very accurate in the regions close to the
> nuclei.
> However, the cube files are  often printed for visualization,
> and high accuracy at the atomic centers is not required.
>
> kind regards
> Marcella
>
>
>
>
> On Dec 13, 4:25 pm, Eva Pluharova <pluha... at gmail.com> wrote:
>> Hi,
>>
>> I am trying to perform all electron calculation of water molecule with
>> print out of all electron density using CP2K version 2.2.366. Input
>> files see in attachment.
>>
>> I obtained following results that I wouldn't expect:
>>
>> 1. Total electronic charge (G-space):      -10.0349568912
>>     Total electronic charge (R-space):      -10.0349568912
>>
>> Why it isn't exactly -10.000000? In other systems that I have tried
>> the discrepancy is significantly higher, for example CH3CONHCH3
>> -40.0000 vs. -41.758.
>>
>> 2. Mulliken population analysis gives the following results:
>> # Atom  Element  Kind  Atomic population                Net charge
>>       1     O        1           7.943086                  0.056914
>>       2     H        2           1.028457                 -0.028457
>>       3     H        2           1.028457                 -0.028457
>>  # Total charge                 10.000000                  0.000000
>>
>> Which aren't in agreement with BLYP/6-31g* (identical basis set)
>> calculation in Gaussian:
>>      1  O   -0.742711
>>      2  H    0.371355
>>      3  H    0.371355
>> that make more sense.
>>
>> 3. Total electronic density printed to cube file doesn't integrate to
>> 10, but something orders of magnitude larger.
>>
>> Any suggestions? Thanks.
>>
>> Best regards,
>> Eva
>>
>>  H2O.inp
>> 2KViewDownload
>>
>>  pos.xyz
>> < 1KViewDownload
>
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