Author Topic: CC2 with COSMO for excited states  (Read 632 times)


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CC2 with COSMO for excited states
« on: July 28, 2021, 12:55:19 PM »
Dear Turbomole forum,
I am currently trying to calculate the excited state energy for small superoxides at the approximate CC2 level of theory including solvation effects via COSMO in the ricc2-module. These systems are open shell systems, containing symmetry elements of the C2v-group. I am simply considering an array of prepared geometries, so the calculations are mostly single-point calculations without a previous optimization of the molecule to the electronic ground state (or any excited state).

Without invocing COSMO (via cosmoprep) these calculations converge readily and I obtain all required excitation energies and properties.
When I include COSMO however the computation always fails in the optimization of the ground state cluster amplitudes.

I oriented myself on the examples in the manual for the calculation of the ricc2-energies:
Code: [Select]
  irrep=a1 nexc=3 npre=3 nstart=3
  exprop states=all relaxed operators=overlap,diplen,angmom,soc
  fop relaxed

and for the COSMO-part:
Code: [Select]
  cosmorel state=(a1 2)

Notably, whichever cosmorel state I use, the error is always the same.
A dscf calculation of the molecule runs smoothly, but the ricc2 calculation after that one gives the following error (given below is the end of the file):

Code: [Select]
   *                                                                        *
   *                                                                        *

   Reaction field calculation using the COSMO solvation model
        Reaction field scheme  : post-SCF                                                                       
        Reaction field density : full unrelaxed                                                                 
        epsilon                :     4.330
        f(epsilon)             :   0.689441
     start CC2 from scratch because restart not enabled

   Iter. MP2 energy       Norm(Omega) Norm(Ombar)   Norm(t1) Norm(t2)  cpu    wall

 internal module stack:

 unfinished (do_t1res and open-shell)
 ricc2 ended abnormally

I am not sure how to fix,  or even interpret this error as something other than CC2 is having internal problems. At first I thought it might have something to do with the OMP_stacksize, but the latter is unlimited on the server I am using. I think with generous $maxcor settings (> 5100 MiB per_core) there should also not be a lack of memory. In addition, decreasing the basis from cc-pVQZ to cc-pVTZ or even cc-pVDZ did not avoid the error.

I am very grateful for your suggestions and help. If additional input/output is required, I will hurry to deliver it.