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

[Jörg Saßmannshausen]

Hi Gerald,
thanks for your reply.

> Did you check if your geometry is correct? 

I have a converged geometry at the mp2/6-31g* level of theory with no 
imaginary frequencies. So I would consider that as 'correct'.

> Angstrom/Bohr-conversion issues 
> might be a problem. Molpro will print the geometry parameters (e.g., bond
> lengths) in both Angstroem and Bohr, and you should check if they are
> sound. It is *very unlikely* that Molpro's RHF will fail to converge a
> reasonable closed-shell organic compound. I don't think I've ever seen that
> happening.

I was using the cartesian coordinates as supplied by Molden. So I would have 
thought it is ok. 
By the way, it finally converged with 125 steps.

>
> Some other things to consider:
> http://www.molpro.net/pipermail/molpro-user/2008-January/002379.html
>
> > I have tried to set it to a (rediculus) high number of 300
> > with the MAXIT keyword, but somehow that seems to be ignored.
>
> "maxit" is not a keyword. It is either a parameter or an option. So you
> generally need to use either
>   {progname,maxit=100}
> or
>   {progname;maxit,100}
> Unfortunately there are still some inconsistencies, with some programs
> accepting only the first form, some only the second, and some accepting
> both...
> But just saying "maxit=100" will simply create a new variable with name
> "maxit" which you can then use in further calculations or as parameter and
> so on.

Ok, I got that from the manual and my understanding was to use it in the same 
way as basis= and geomtyp= 
Thanks to Kirk's earlier email it seems to work now.

Thanks for your suggestions!

All the best

Jörg




-- 
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Jörg Saßmannshausen
Research Fellow
University of Strathclyde
Department of Pure and Applied Chemistry
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