[molpro-user] Unclear problem in EOM-CCSD calculations: "small eigenvalue of S-eff matrix ... This can lead to convergence problems!"

[Evgeniy Gromov]

Hello,

I encountered some unclear problem when doing EOM-CCSD calculations
for an Ir complex. All steps till EOM went fine, but in EOM I get the
following warning:

  The smallest eigenvalue of S-eff matrix     0.8656157915E-13
  This can lead to convergence problems!

and two of the five roots do not seem to have converged; there is
no  "Converged" message for them after 50 iterations.

I wonder what this could be caused by? Could it be due to a very high
in energy (63.5 hartree) virtual orbital?

Best regards,
Evgeniy

-- 
Dr. Evgeniy Gromov
Theoretische Chemie
Physikalisch-Chemisches Institut
Im Neuenheimer Feld 229
D-69120 Heidelberg
Germany

Telefon: +49/(0)6221/545213
Fax: +49/(0)6221/545221
E-mail: evgeniy.gromov at pci.uni-heidelberg.de