[molpro-user] CASPT2 error

[Gerald Knizia]

On Wednesday 05 January 2011 22:21, Alexander Sokolov wrote:
> [...] However, when I'm running calculations for the 3d and 4th excited
> states, CASPT2 calculation gives a very strange error: NO CONVERGENCE
> IN REFERENCE CI AFTER 50 ITERATIONS. DEMAX=  0.87D-07
> VRMAX=  0.17D-07 
>
>  PLEASE INCREASE MAXITI AND RETRY!

You could try calling rs2c with
  {rs2c,maxiti=200,shift=0.3,thrvar=1.0d-8,thrden=1.0d-8;maxit,100;state,1,4}
instead of
  {rs2c,shift=0.3,thrvar=1.0d-8,thrden=1.0d-8;maxit,100;state,1,4}

Does that work?

> My CASSCF calculation converges in 13 iterations, so the convergence
> shouldn't be a problem.

A CASSCF iteration corresponds to updating the orbitals one time. The 
non-convergence message above refers to a different meaning of iteration: 
Namely, the determination of CI coefficients (optimization of the 
coefficients of configurations) in the internal space during the rs2c 
calculation; these numbers would be closer to what multi outputs under the 
NCI lines in its output.
-- 
Gerald Knizia