[molpro-user] rhf convergence problems

[Hans-Joachim Werner]

This seems top be a difficult case, but you can converge it using  
multi, e.g.,

  {rhf;maxit,20
  shift,-0.3,-0.3;
  wf,charge=-1}
  {multi;occ,44;closed,43;wf,charge=-1;}

Best regards
Joachim Werner
Am 12.05.2010 um 18:31 schrieb Jose A. Gamez:

> Dear all,
>
> I'm trying to perform a CCSD(T) calculation on a radical-anionic  
> molecule.
> However, I have great troubles to converge the ROHF calculation (the  
> UHF
> converges OK). I've tried a couple of things:
>
> * I've used a smaller basis set (sto-3g and dvz, although the ROHF dvz
> calculation didn't converge) RHF calculation as initial guess of my  
> ROHF
> calculation.
>
> * I've used the restricted orbitals of the neutral molecule as  
> initial guess.
>
> * I've increased the value of the shift of the open orbitals up to  
> -0.3 .
>
> I think that the origin of this problem is that there is an excited  
> state
> lying close to the ground state. But, since I optimised the UHF  
> wavefunction,
> I would like to converge the ROHF.
>
> You have any tips?
>
> Thanks a lot for your help.
>
> Cheers,
>
> Jose
>
> P.D. I include the input file if that helps
>
> ***, CCSD(T) avtz calculation
>
> !basis=sto-3g
>
> geomtyp=xyz
> geometry={
> 8
> Title
>   Se           0.119746   -0.439567    0.252388
>   Se           0.214836    0.063065    2.534400
>    C           1.973623    0.030962   -0.199635
>    H           2.638913   -0.492006    0.483666
>    H           2.169261   -0.260569   -1.233496
>    H           2.091656    1.105526   -0.073333
>    O           1.479630   -2.438497    2.672993
>    H           0.982562   -2.250200    1.856981
> }
>
> !{rhf;
> ! wf,charge=-1;
> ! print,orbitals;
> !}
>
> basis=vdz
> rhf
> {rhf;
> shift,-0.3,-0.3;
> wf,charge=-1}
>
> basis=avtz
> !print,basis
>
> !rhf
> {rhf;
> wf,charge=-1;
> shift,-0.3,-0.3;
> ! print,orbitals;
> }
>
> put,molden,CH3SeSeOH-TSOHan.TZ.molden
>
> pop
> {pop;
> density,spin}
>
> uccsd(t)
> ---
>
>
> -- 
> Jose A. Gamez
>
> Departamento de Química, C-13
> Universidad Autonoma de Madrid
> Cantoblanco, 28049-Madrid. Spain
> Phone: +34-91-497-3854
> FAX: +34-91-497-5238
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