[Ifeffit] Muffin tin radius adjustment?

[Paul Fons]

    I am trying to analyze some XAFS data on a Sb-Te compound and  
when I run feff(6) I get errors regarding the coordination number  
being too small implying the muffin tin radius is too big.  In this  
material the first nearest neighbor bond length is about 3 angstroms  
(slightly more or less depending on the site).  I assume this is  
related to the cause of the problem.  Any suggestions as to how to  
fix/avoid this sort of problem?  feff6 output is pasted below.   
Interestingly enough, feff8 does not output any error messages and  
the sum of the paths looks identical (at least at first glance).  Is  
this a false error message or (more likely) has feff8 become more  
intelligent with regards to defining the muffin tin radius?

Feff6 output

  Calculating potentials and phases...
      free atom potential and density for atom type    0
      free atom potential and density for atom type    1
      free atom potential and density for atom type    2
      overlapped potential and density for unique potential    0
      overlapped potential and density for unique potential    1
      overlapped potential and density for unique potential    2
      muffin tin radii and interstitial parameters
      phase shifts for unique potential    0
    Hard tests failed in fovrg.
   Muffin-tin radius may be too large; coordination number too small.
      phase shifts for unique potential    1
    Hard tests failed in fovrg.
   Muffin-tin radius may be too large; coordination number too small.
      phase shifts for unique potential    2
    Hard tests failed in fovrg.
   Muffin-tin radius may be too large; coordination number too small.
Preparing plane wave scattering amplitudes...
    nncrit in prcrit       9
Searching for paths...
     WARNING in PATHS Module:
        rmax > distance to most distant atom.
        Some paths may be missing.
    rmax, ratx     15.50000    15.40291
      Rmax 15.5000  keep and heap limits   0.0000000   0.0000000
     Preparing neighbor table


Feff8 output

Calculating potentials ...
     free atom potential and density for atom type    0
     free atom potential and density for atom type    1
     free atom potential and density for atom type    2
     initial state energy
     overlapped potential and density for unique potential    0
     overlapped potential and density for unique potential    1
     overlapped potential and density for unique potential    2
     muffin tin radii and interstitial parameters
iph, rnrm(iph)*bohr, rmt(iph)*bohr, folp(iph)
     0  1.79879E+00  1.71274E+00  1.13279E+00
     1  1.81342E+00  1.72495E+00  1.13595E+00
     2  1.83703E+00  1.74437E+00  1.14149E+00
mu_old=    -0.508
Done with module 1: potentials.
Calculating LDOS ...
               LDOS calculation for specified grid
Calculating energy and space dependent l-DOS.
It takes time ...
      potential type  0
      potential type  1
      potential type  2
Calculating chi and rho...    0
Calculating chi and rho...    1
Calculating chi and rho...    2
Done with LDOS.
Calculating cross-section and phases...
     absorption cross section
     phase shifts for unique potential    0
     phase shifts for unique potential    1
     phase shifts for unique potential    2
Done with module 2: cross-section and phases...
Done with module 3: FMS.
Preparing plane wave scattering amplitudes...
Searching for paths...
    WARNING:  rmax > distance to most distant atom.
              Some paths may be missing.
              rmax, ratx   1.55000E+01  0.00000E+00
     Rmax 15.5000  keep and heap limits   0.0000000   0.0000000
     Preparing neighbor table



Dr. Paul Fons
Senior Researcher
National Institute for Advanced Industrial Science & Technology
METI
Center for Applied Near-Field Optics Research (CANFOR)
AIST Central 4, Higashi 1-1-1
Tsukuba, Ibaraki JAPAN 305-8568

tel. +81-298-61-5636
fax. +81-298-61-2939

email: paul-fons at aist.go.jp

The lines below are in a Japanese font

〒３０５−８５６８
茨城県つくば市東１−１−1
つくば中央第４
近接場光応用工学センター
ポール・フォンス主任研究官

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