[molpro-user] Optimisation to a minimum

Kirk Peterson kipeters at wsu.edu
Fri Oct 24 15:45:34 BST 2008


do you have any symmetry restrictions in your z-matrix input (2 or  
bond lengths set equal to each other, dihedral angles fixed to 180,  
etc.)?  If you optimize under symmetry constraints you will not locate  
the global minimum if it has lower symmetry.

just a guess,


On Oct 23, 2008, at 3:42 PM, Jayashree wrote:

> I am trying to optimise to a minimum geometry, which means that I  
> should get all positive frequencies for the normal modes. By  
> default, I know that MOLPRO does a search for a minimum. But in my  
> output, even though it has completed the optimisation in 5 steps, it  
> still gives me one imaginary frequency in the search for a minimum.  
> I am not sure what is wrong, since the optimisation seems to be  
> complete, yet its unable to locate a minimum. Any input/suggestion  
> would be helpful..
> -- 
> Jayashree
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