Question: CC2 D1 diagnostic

[Stephan]

I have a question about the currently implemented D1 diagnostic in the ricc2 module.
The manual states that  it is implemented as described in

C. L. Janssen; I. M. B. Nielsen. New diagnostics for coupled-cluster and
Møller-Plesset perturbation theory. Chem. Phys. Lett., 290(4–6), 423, (1998)

, which is clearly a labelled a diagnostic for closed-shell systems.
Further investigation brought up

L.Leininger et al. A new diagnostic for open-shell coupled-cluster theory.
Chem. Phys. Lett., 328, 431-436 (2000)

where a D1 diagnostic similar to the one discussed above for ROCCSD is proposed, and

T.J. Lee, Comparison of the T1 asnd D1 diagnostics for electronic structure theory:
a new definition for the open-shell D1 diagnostic. Chem. Phys. Lett., 372, 362-367 (2003)

where it is argued that the definition of the D1(ROCCSD) diagnostic of Leininger et al.
is arbitrary.

As only the first paper is cited within TM, I wonder how the D1 diagnostic for CC2 calculations based on UHF WF's
is implemented and wether it can be used to evaluate the quality of my calculations.

Regards,
Stephan.

[christof.haettig]

It's true that there is an issue with the D1 diagnostic for ROMP2 and ROCC2 calculations, which presently are ignored
in the implementation in ricc2.
But I'm not aware of problems for UHF based open-shell calculations: here the diagnostic should work fine. The only
problem is that there is little experience and/or reference data for it in the literature.

Christof