Electric Field Gradient.

[Chris Wigglesworth <C.Wigglesworth-0at0-open.ac.uk>]

 I wonder if someone could explain to me the reason for the differing EFG
 values I am obtaining from GAMESS and Gaussian94 even though I am using
 almost identical models and both programs seem to calculate the EFG in the
 same way.
 My model includes a central Lithium with basis set (BS) 6-31G*,
 surrounded by six oxygens with BS 6-31+G*, the rest of the model is
 completed with atoms with a 3-21G basis set and surrounding point charges
 to make the model neutral. It is the same for both programs except that I
 believe Gaussian94 uses 5D functions by default as opposed to GAMESS
 which uses 6 and I am not sure that the default polarisation and diffuse
 function values are the same for both programs.
 The principal axis frame values of the EFG tensor given by the two programs
 for this model is,
 EFG              XX         YY         ZZ
 GAMESS       -0.001736  -0.001732  -0.003468
 Gaussian94   -0.003731  -0.003726  -0.007457
 Is the large difference due to the differing polarisation parameters, or
 the diffuse function values? I wouldn't have thought that the default
 values differed enough to make this large of a difference, so is there
 another reason?
 I will post a summary of any responces that I get.
 Chris Wigglesworth.
 Research Student
 The Open University
 Walton Hall
 Milton Keynes
 MK7 6AA
 Tel:(01908) 653896
 e-mail: c.wigglesworth-0at0-open.ac.uk
 * In my final year and looking for a job! :-) *