[molpro-user] SCF Convergence Problem within the SURF program

[Zygmunt Flisak]

Hello,

I am trying to calculate the VSCF formamide anharmonic frequencies using different basis sets. For the pc2 and 6-31G* basis sets, the first occurrence of RHF-SCF (invoked by the potential energy surface program SURF) does not converge. I tried several methods to solve this problem - including increasing the number of SCF cycles, applying level shifting and playing with the DIIS parameters - but to no avail. However, for larger basis sets, such as aug-pc2, the SCF converges without any problem.

Is there any solution to get the SCF converged in this case?

Best regards,
Zygmunt Flisak