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Today's Topics:

   1. Re: FEff (Matt Newville)
   2. Trouble creating feff input file for NaTiO3 cubic perovskite
      structure (Badari Rao)
   3. Re: Trouble creating feff input file for NaTiO3 cubic
      perovskite structure (Bruce Ravel)


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Message: 1
Date: Mon, 29 Sep 2014 12:47:57 -0500
From: Matt Newville <newville@cars.uchicago.edu>
To: XAFS Analysis using Ifeffit <ifeffit@millenia.cars.aps.anl.gov>
Subject: Re: [Ifeffit] FEff
Message-ID:
        <CA+7ESbqpUvDtwnjXumeqWo2DMwvw15nyUOfjPq5jnV8t5EJviw@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

On Mon, Sep 29, 2014 at 11:48 AM, Bruce Ravel <bravel@bnl.gov> wrote:

> On 09/29/2014 11:44 AM, Carlos Triana Estupinan wrote:
>
>> Dear
>> Feff group
>>
>> I am Carlos Triana, and I want ask you the following.
>> I am trying to calculate the feff.inp file for a theoretical amorphous
>> structure composed by a supercell with 24 Ti atoms surrounding by 48
>> oxygen atoms with different coordination. In amorphous materials or
>> materials with distortions from regular crystals, the absorbing atoms
>> may have different surroundings.
>> My question is how can I build the feff.inp file in this case, shall I
>> define the 24 Ti atoms like absorbing atoms, because in this case the
>> feff does not works.
>> What can I do in this case, how can I build the feff.inp file with
>> different environments
>>
>> I will be very grateful for your help
>>
>
> I'd like to follow up on Matt's comment.
>
> I presume you have some way of knowing a list of Cartesian coordinates for
> the atoms in your cluster.  If so, the discussion on pages 7-10 of this
> talk should be helpful, with the caveat that your input file needs to be
> appropriate to the version of Feff you intend to use.
>
> https://speakerdeck.com/bruceravel/modeling-non-
> crystalline-samples?slide=9
>
> Make one input file for each Ti atom serving as the absorber.  As Matt
> said, take care not to overwrite your results.
>
> Were this my problem, I would prefer to organize and perform N
> calculation, then add them up myself.  That said, Feff does provide a
> simple sort of configuration average.  Look up "CFAVERAGE" in the Feff
> document.
>
> B
>


I believe CFAVERAGE does not work as advertised.  I haven't checked this
recently, but my recollection is that using CFAVERAGE always ends up giving
a coordination number that is a whole number, which cannot always be the
case.  That might depend on versions of Feff, and I'd be happy to shown to
be wrong about this.

Can anyone else verify or shed light on this?

 --Matt
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Message: 2
Date: Tue, 30 Sep 2014 15:15:12 +0530
From: Badari Rao <badari.rao@gmail.com>
To: ifeffit@millenia.cars.aps.anl.gov
Subject: [Ifeffit] Trouble creating feff input file for NaTiO3 cubic
        perovskite structure
Message-ID:
        <CAM=6XwBpwofyOJGk8pRpR6H=xA=DzKWOhHEG3-qgDKPaHE-yvw@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Dear All,
When I try to feed the following data into the atoms input and run the feff
calculations, the software just automatically closes.
space group no: 221
a = b = c = 3.88; alpha = beta = gamma = 90;
atomic coordinates:
Na: 0.5, 0.5 , 0.5
Ti:   0,    0,    0
O:   0,    0,    0.5

Core: Ti

I don't think it is a bug because the calculation works perfectly when I
replace Na with heavier atoms like K, Mg etc. I would like to know why I am
not able to create the feff input file using Na.

-- Yours Sincerely
Badari Narayana. A. R.
Ph.D Student, Nanoscience and Nanotechnology,
c/o Prof Rajeev Ranjan,
Electroceramics Lab,
Department of Materials Engineering,
Indian Institute of Science.
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Message: 3
Date: Tue, 30 Sep 2014 08:21:18 -0400
From: Bruce Ravel <bravel@bnl.gov>
To: XAFS Analysis using Ifeffit <ifeffit@millenia.cars.aps.anl.gov>
Subject: Re: [Ifeffit] Trouble creating feff input file for NaTiO3
        cubic perovskite structure
Message-ID: <542AA03E.8070701@bnl.gov>
Content-Type: text/plain; charset=windows-1252; format=flowed

On 09/30/2014 05:45 AM, Badari Rao wrote:
> Dear All,
> When I try to feed the following data into the atoms input and run the
> feff calculations, the software just automatically closes.
> space group no: 221
> a = b = c = 3.88; alpha = beta = gamma = 90;
> atomic coordinates:
> Na: 0.5, 0.5 , 0.5
> Ti:   0,    0,    0
> O:   0,    0,    0.5
>
> Core: Ti
>
> I don't think it is a bug because the calculation works perfectly when I
> replace Na with heavier atoms like K, Mg etc. I would like to know why I
> am not able to create the feff input file using Na.

I cannot reproduce your problem using the information you've given.
That structural data runs just fine and gives sensible output on both
Windows and linux.

When making a bug report, you should include the information discussed
in http://bruceravel.github.io/demeter/pods/bugs.pod.html.  Without the
information in the error log and without an actionable recipe for
replicating the problem, there is simply nothing that I can do to help.

B


--
  Bruce Ravel  ------------------------------------ bravel@bnl.gov

  National Institute of Standards and Technology
  Synchrotron Science Group at NSLS --- Beamlines U7A, X24A, X23A2
  Building 535A
  Upton NY, 11973

  Homepage:    http://bruceravel.github.io/home/
  Software:    https://github.com/bruceravel
  Demeter:     http://bruceravel.github.io/demeter/


------------------------------

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End of Ifeffit Digest, Vol 139, Issue 23
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