Dear List,
I have noticed that EXAFS fits to Au foils at 298 K underestimate the known equilibrium bond length. According to the CRC Handbook the lattice constant at 298 K is 4.0782 +/- 0.0002 Å. This is a bond length of 2.884 Å. However, in published EXAFS work[1] as well as fits that I have performed the bond length is about 2.867 Å. The error is small -- about half a percent too short -- but I am interested in using EXAFS to study relatively small changes in bond length and I am curious about the resolution that can be achieved.
I want to understand the source of this error. I think the two biggest sources of error would be correlation between variables in the fitting model and errors in the theoretical standard (FEFF6 in this case). The random experimental error for a foil should be negligible. I would like to know if it is possible to create a better theoretical standard using a more ab initio approach.
Is anyone aware of any other software for performing more accurate EXAFS calculations? It is okay if it is a very expensive calculation as I have plenty of computer time.
I have seen that some DFT packages can perform XANES calculations, but I have seen no mention of EXAFS.
Thanks,
Sam Chill