Recent Posts

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21
Ricc2 / Re: frequency mismatch in cc density module
« Last post by christof.haettig on March 24, 2024, 05:41:41 PM »
It should not happen with newer versions.

If it happens (with older versions) you can fix it by
  - run an initial calculation with higher convergence threshold in $excitations
  - if it stops with this error, restart with a reduced convergence threshold.
It typically happens if you have (near) degeneracies between states within the same computational irrep. Thus, if your structure has any point group symmetry, use it in the calculation.
22
Ricc2 / Re: Queerness/Issue observed with RI-basis set
« Last post by christof.haettig on March 24, 2024, 05:37:46 PM »
Just two remarks:
   - once the (main) basis set describes the HF wavefunction good enough the MP2 energy does converge monotonically the from above to the
      MP2 basis set limit
   - the difference between the RI-MP2 and the MP2 energy as coulomb and exchange correlation contributions and is not a positive definite quantity.
     Thus it can fluctuate around 0 and accidentially be for a given compound and structure close to 0 for a small auxiliary basis. There is nothing like
     a Ritz variational theorem for it. But for systematically optimized basis sets the errors go on average systematically down.
     With the "consistent" combinations of main and auxiliary basis sets the RI error in the MP2 energy should be small compared to the remaining
     (orbital) basis set error in the MP2 energy.
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ccsdf12 / Re: (T) bit of CCSD(T) calculation taking forever
« Last post by christof.haettig on March 24, 2024, 05:23:02 PM »
Just a warning: The operation count for the (T) scales with as O(N^7) with the system size N. The CCSD part of as O(N^6). Thus for larger systems the triples correction can take order of magnitudes longer than the CCSD calculation.
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ccsdf12 / Re: CCSD(T)-pVTZ calculations with BSSE correction
« Last post by christof.haettig on March 24, 2024, 05:15:16 PM »
I suggest that you contact the support or the developers.
25
ccsdf12 / Re: There is at least one positive pair energy in the explicitly correlated part!
« Last post by christof.haettig on March 24, 2024, 05:13:05 PM »
I suggest that you contact directly the support or the developers.
26
ccsdf12 / Re: CCSD single and doubles amplitudes
« Last post by christof.haettig on March 24, 2024, 05:02:11 PM »
The file with the singles amplitudes can be read and converged to ASCII with the ricctools program. But there is no such option yet for the doubles amplitudes.
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ccsdf12 / Re: Two particle density matrix generation
« Last post by christof.haettig on March 24, 2024, 04:58:58 PM »
No. Sorry, this is not implemented.
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Ricc2 / Re: Geometry optimization of the lowest triplet state
« Last post by christof.haettig on March 24, 2024, 04:53:44 PM »
The MP2 codes in TURBOMOLE can't do geometry optimizations for restricted open-shell Hartree-Fock reference functions. That is only possible of unrestricted Hartree-Fock references. You can set that by requesting parallel spins for the ``unpaired`` electrons through $alpha shells and $beta shells and then do the geometry optimization as usual for UHF-based MP2.
But you need to check the Hartree-Fock output for the amount of spin-contamination...
29
TURBOMOLE Forum General / Re: Two-photon absorption calculations
« Last post by christof.haettig on March 24, 2024, 04:48:49 PM »
Is your question related to any of the TURBOMOLE programs (escf or ricc2) or do you just ask generally?
30
Treatment of Solvation Effects with COSMO / Re: cc2cosmo/ricc2 fails with CC2
« Last post by christof.haettig on March 24, 2024, 04:46:17 PM »
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.
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