cc2cosmo/ricc2 fails with CC2

[marius]

Dear all,

I tried to run ricc2 calculations with COSMO using version 7.0, the cc2cosmo script and the options given in the manual. The calculations run well with the ADC(2) model, but with CC2, the response calculation terminates with the error

Warning: one or more of the second eigenvectors do not give correct excitation energies:
 Largest difference between left and right eigenvalues is  0.69E-03 a.u. for state no.  1

 ========================
  internal module stack:
 ------------------------
    ricc2
    cc_exci
 ========================

 PROBLEM WITH LE/RE EIGENVALUES!
 ricc2 ended abnormally

This seems to be a general issue, regardless of the system, I tried, e.g., H2O in water with SV(P) basis:

$ricc2
  cc2
$response
  fop relaxed
$excitations
  irrep=b2  multiplicity=1  nexc=1 npre=1
  exprop relaxed states=all
$cosmo
  epsilon=   80.400
  rsolv= 1.30
  refind= 1.333
  cosmorel state=(b2 1)
$cosmo_atoms
 ...

[Arnim]

Hi,

CC2/COSMO excitation is not yet (status version 7.0) implemented.

Cheers,

Arnim

[shafikoff]

Hello,

Do I understand it right that COSMO is still not implemented to run at CC2 level in version 7.7?

[christof.haettig]

COSMO-CC2 is implemented in ricc2 and available in the release versions since some years within the post-SCF coupling scheme.
The problem is that you use cosmoprep and cc2cosmo which were coded for Lunkenheimer and Koehn for COSMO-ADC(2) with the PTED coupling scheme. The name of cc2cosmo is misleading, yes, but it wasn't my idea... It should have been called something like pted.

How to use COSMO-CC2 with the post-SCF coupling scheme is described in the documentation.