Trouble-Shooting FEFF Problems

 

FEFF8 has been extensively tested but occasionally new bugs show up. In an effort to maintain portable and trouble-free codes we take all bug reports seriously. Often we receive reports by users of older versions of FEFF of bugs that have been fixed in the latest releases. Other code failures can often be traced to input file errors, sometimes quite subtle.

Some known difficulties are:

• Non-physical widely spaced distributions of atoms. Symptoms of this common problem are very large muffin-tin radii (see the header of any '.dat' file) and possibly a failure of the phase-shift program to converge. This gives error message hard test fails in fovrg.
• An error in assigning potential indices; the first atom with a given potential index must have the geometry representative of this potential type. This is sometimes fixed by using a somewhat larger cluster; in fact it is usually desirable to have a larger cluster for potential construction than that used in the XAFS calculation due to errors in the potentials at surfaces. Unless the atom distribution is physically possible, you can expect the code to have problems.
• Hash collision in the pathfinder. This is now rare, but can usually be corrected simply by changing distances in the fourth decimal place.
• For the and higher edges you may receive the error message like: Lambda array overfilled. The calculations should be repeated with IORDER -70202 card.