[Ifeffit] Interpolating in feff - the Lead Titanate example

[Matt Newville]

Hi Joseph,

I think this thread may have gone under-noticed, so sorry for not responding.

This seems like a really strange situation (how could Feff be getting
path distances wrong??), but I suspect from your message that you may
have been deliberately playing with the intermediate Feff files and
re-running certain modules.   In that case, it would be possible to
get these seemingly inconsistent results.    For example, is it
possible that you deliberately moved the Sb atom from
    0.0000   -5.7395   -1.0213  2  51 Sb
to
    0.0000   -5.9179    0.0000  2  51 Sb

after running through the full calculation once, and then only running
the path finder and genfmt on the distorted structure?

That is: can you explain what you did in more detail?

Thanks,

--Matt


On Fri, Jun 19, 2009 at 10:19 AM, Joseph Washington<breaditor2 at gmail.com> wrote:
> Hello all,
> I'm applying the principle of interpolation in order to find the
> buckling angle in a similar system to the lead titanate example. And
> though I'm sure that my path.dat list contains paths of identical reff,
> my generated feffNNNN.dat files are changing the path lengths for beta=0
> and beta=20. I think it has something to do with rounding in feff - am i
> right? See below - FEFF1019 = beta 0 degrees, FEFF2019 = beta 20
> degrees, and relevant part of paths.dat file.
>
> Thanks for your assistance!
>
> Joseph
>
> ---------------> FROM FEFF2019.dat
>   4   4.000   5.9211    3.6223   -3.72616 nleg, deg, reff,
> rnrmav(bohr), edge
>         x         y         z   pot at#
>      0.0000    0.0000    0.0000  0  32 Ge       absorbing atom
>      0.0000   -2.9590    0.0000  1  52 Te
>      0.0000   -5.7395   -1.0213  2  51 Sb
>      0.0000   -2.9590    0.0000  1  52 Te
>
>
> ------------------> FROM FEFF1019.dat
>    4   4.000   5.9179    3.6223   -3.72616 nleg, deg, reff,
> rnrmav(bohr), edge
>         x         y         z   pot at#
>      0.0000    0.0000    0.0000  0  32 Ge       absorbing atom
>      0.0000   -2.9590    0.0000  1  52 Te
>      0.0000   -5.9179    0.0000  2  51 Sb
>      0.0000   -2.9590    0.0000  1  52 Te
>
>
>
> -------------------------------> FROM PATHS LIST
>     1019    4   4.000  index, nleg, degeneracy, r=  5.9179
>       x           y           z     ipot  label      rleg      beta
>     eta
>     0.000000   -2.958950    0.000000   1 'Te    '
>     0.000000   -5.917900    0.000000   2 'Sb    '
>     0.000000   -2.958950    0.000000   1 'Te    '
>     0.000000    0.000000    0.000000   0 'Ge    '
>
>     2019    4   4.000  index, nleg, degeneracy, r=  5.9179
>       x           y           z     ipot  label      rleg      beta
>     eta
>     0.000000   -2.958950    0.000000   1 'Te    '
>     0.000000   -5.739453   -1.021255   2 'Sb    '
>     0.000000   -2.958950    0.000000   1 'Te    '
>     0.000000    0.000000    0.000000   0 'Ge    '
>
> --
> Joseph Washington
> Research Assistant
> Department of Physics
> North Carolina State University
> 431 Riddick Hall
> Raleigh, NC 27695-8202
> email: jswashin at ncsu.edu
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