[no subject]

From: theresa -8 at 8- si.fi.ameslab.gov (Theresa Windus)
Date: Wed, 29 Jul 1992 11:49:15 -0500
 Fellow netters:
   I have recently had the chance to use Gaussian92 for an MP2 analytical
 hessian run on a structure that I had optimized using Gaussian88.  Much to
 my surprise, I found that the default is to use the frozen core unstead of
 the full correlation option.  It was my understanding (however wrong this
 may be) that the full correlation is needed when doing MP derivatives.  I
 have not been able to track down a paper that discusses the use of the
 frozen core for the derivatives.  If someone out there knows of the
 reference or understands the mathematics behind this, I would be most
 appreciative of any help.  Also, any experience between the difference in
 structures and frequencies obtained by the two methods would be useful.
 Thanks,
 Theresa Windus
 Department of Chemistry
 Iowa State University
 Ames, IA  50010
 e-mail:  theresa -8 at 8- si.fi.ameslab.gov
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