Subject: PES scan in G98

From: Jamie Platts <[email-masked]>
Date: Fri, 26 Jul 2002 09:55:03 +0100 (BST)

Dear CCLers,

  When running PES scans in G98 using Opt=ModRedundant, I often get 
errors such as below:

 Iteration 99 RMS(Cart)=  0.00000107 RMS(Int)=  0.00536936
 Iteration100 RMS(Cart)=  0.00000107 RMS(Int)=  0.00536908
 Curvilinear step not converged.
 Error imposing constraints
 Error termination via Lnk1e in /home/colossus/jamie/g98/l103.exe.

which seems to be just short of convergence. I can't see anything in the
manual which might relax this criterion, or allow more iterations, so I'm
a bit stuck. Does anyone have any idea how I can fix this? Am I simply
using too large a step size (30 degrees in a dihedral in this case)?

----------------------------------------------------------
  Jamie Platts 							 
  Dept. of Chemistry  		Phone: +44 (0) 2920 874950		 
  Cardiff University 	 	Email: [email-masked]		 
  P.O. Box 912 			FAX:   +44 (0) 2920 874030		 
  Cardiff CF10 3TB 		www.cf.ac.uk/chemy