[Wien] core electrons leaking out of MT-sphere

[Christine Frayret]

Dear Lyudmila,

I have found B-B distance in agreement with authors. All the distances I
have found are indeed very close to the distances issued from Find-It for
this structure (see below).

Distances from find-it :             Distances from initialization :

B   1 +3 | B   1 +3 | 1.035           1.03502
         | B   1 +3 | 1.035
         | B   1 +3 | 2.744
         | B   1 +3 | 2.744

B   1 +3 | O   1 -2 | 1.368            1.36765
         | O   1 -2 | 1.368
         | O   1 -2 | 1.368
         | O   1 -2 | 1.368
         | O   1 -2 | 1.368
         | O   1 -2 | 1.368

B   1 +3 | O   2 -2 | 1.464              1.46445
         | O   2 -2 | 1.571                  1.57061
         | O   2 -2 | 1.887                  1.88701
         | O   2 -2 | 1.921                  1.92072
         | O   2 -2 | 2.459
         | O   2 -2 | 2.523
         | O   2 -2 | 2.630
         | O   2 -2 | 2.714

B   1 +3 | Y   1 +3 | 2.917            2.91665
         | Y   1 +3 | 2.917
         | Y   1 +3 | 2.968
         | Y   1 +3 | 2.968

Y   1 +3 | Y   1 +3 | 3.776            3.77600
         | Y   1 +3 | 3.776
         | Y   1 +3 | 3.776
         | Y   1 +3 | 3.776
         | Y   1 +3 | 3.776
         | Y   1 +3 | 3.776

Y   1 +3 | O   1 -2 | 2.386            2.38666
         | O   1 -2 | 2.386
         | O   1 -2 | 2.386
         | O   1 -2 | 2.386
         | O   1 -2 | 2.386
         | O   1 -2 | 2.386
         | O   1 -2 | 2.387
         | O   1 -2 | 2.387
         | O   1 -2 | 2.387...

Y   1 +3 | O   2 -2 | 2.322            2.32235
         | O   2 -2 | 2.322
         | O   2 -2 | 2.322
         | O   2 -2 | 2.322
         | O   2 -2 | 2.322
         | O   2 -2 | 2.322

    I believe the problem with the struct file comes from the fact I didn't
notice that the site occupancy of O2 (6h) and B(6h) atom was 1/3 whereas it
is of 1 for Y(2b) and O1 (4f). This leads to Y2B2O6 = 2*YBO3 which is in
accordance with the value of Z for this structure : Z = 2. This is also
consistent with the YO8 polyhedra made of 2 O2(6h) and 6 O1(4f).

How can I introduce a site occupancy into the w2web interface ?

Thank you very much for your help,

Best regards,

Christine Frayret

----- Original Message -----
From: "Lyudmila Dobysheva" <lyu at otf.pti.udm.ru>
To: "A Mailing list for WIEN2k users" <wien at zeus.theochem.tuwien.ac.at>
Sent: Saturday, February 18, 2006 4:07 PM
Subject: Re: [Wien] core electrons leaking out of MT-sphere


> Dear Christine,
>
> > this calculation along with the enclosed initial struct file I used.
> > Chadeyron, G. et al, Journal of Solid State Chemistry 1997 128 261
>
> I am not a specialist in these compounds, so, maybe, I am writing
completely
> wrong things, but nevertheless:
>
> 1. Usually the chemical formula shows the composition of atoms, you and
the
> above paper declare YBO_3, but the struct file gives Y_2 B_6 O_10
>
> 2. Some papers describes the coordination of boron as B_3O_9. In your
> structure there is B_3O_8. The above paper says about "fourfold
> coordinated  boron  atoms" (I could find only abstract), this agrees to
B_3O_9
> structure. Your struct file gives environment of B as 2 B atoms and next
> oxygens at longer distances.
>
> 3. In the papers I have seen, I never met the B-B distance as closest,
always
> B-O, for example
> Chem. Mater. 2004, 16, 2418-2424
> Structures and Phase Transition of Vaterite-Type Rare
>    Earth Orthoborates: A Neutron Diffraction Study
>  Jianhua Lin, Denis Sheptyakov,*, Yingxia Wang, and Peter Allenspach
>
> 4. The above paper (abstract) says: "The  structure  exhibits two
> nonequivalent environments  for the yttrium ions", you have only one
(though
> the authors may think some other nonequivalency).
>
> Large suspicion that you are working with a wrong struct file.
>
> Best wishes
>  Lyudmila Dobysheva
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