Random-phase approximation , open-shell

Zuchowski PS, Bussery-Honvault B, Moszynski R, Jeziorski B (2003) Dispersion interaction of high-spin open-shell complexes in the random phase approximation. J Chem Phys 119 10497-10511... 

Bartlett looks a lot like the usual random phase approximation (discussed later). The same authors also expressed the THDF approach in terms of the sum-over-states procedure and discussed the effects of truncation with this context. Recently, Kama extended the AO-based THDF procedure to open-shell systems using a UHF-like approach. 

On the basis of an SCF closed shell or UHF open shell parent state, electronic excitations can be treated on the singles Cl (SCI) and SCF-RPA (RPA = random phase approximation) level. On the DFT level one can compute excitations of closed shell parent states for the common functionals, the RI option is supported for nonhybrid functionals. 

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