[molpro-user] CCSD(T) RHF not converging

Jörg Saßmannshausen jorg.sassmannshausen at strath.ac.uk
Thu Jul 30 10:30:41 BST 2009

Dear Gerald,

> This is an issue of molecule input (wrong units, missing atoms, wrong
> format, wrong number of electrons/occupations etc). A formally "correct"
> geometry won't help you if the bond lengths are off by a factor of two due
> to unit conversion errors.

Thanks for that hint, I think that was actually the problem.
I read in the manual the MolPro accepts xyz coordinates, so I was using the 
coordinates generated by the program which did the MP2 calculation as input. 
What I did overlook was that it also included the atomic charge (i.e. 6 for 
C) in the 2nd column. My wrong.

> If RHF requires 125 iterations for a well-behaved closed-shell molecule,
> then something is wrong. And I'd bet that it's not the RHF program.

Yes, you were right. 

I hope the problem is now sorted, it seems to converge after 10 steps. 
Meanwhile I have gabedit installed so I can view the output file visually, 
which makes it easier to see if the input-geometry got somehow messed up.

Thanks again for your help!


Jörg Saßmannshausen
Research Fellow
University of Strathclyde
Department of Pure and Applied Chemistry
295 Cathedral St.
G1 1XL

email: jorg.sassmannshausen at strath.ac.uk
web: http://sassy.formativ.net

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