[molpro-user] HF convergence

[Yann Tambouret]

Hey Molpro user group,

I'm using HF orbitals in a CI calculation of NO, and I am doing a three 
point calculation to do NACME calculations.
At one geometry, I was getting the following error message during one of 
the HF calculations:

 ?APPARENTLY NO CONVERGENCE, EXIT AFTER THREE FURTHER ITERATIONS

and the HF run would stop, as it says, after three more iterations. To 
prevent this from happening, I set the MAXDIS variable to 35, which 
helped converge for this problematic geometry.

The problem now is that at that geometry, the displaced geometries (+/- 
dr) do not converge, and produce the same message written above.

What are some of the reasons HF might have trouble converging? What 
advice could you offer me to solve these convergence issues?

Thanks for your time,

Yann Tambouret
BU Chemistry