Molecular electric quadrupole moments calculated with matrix dressed SDCI

We have calculated the molecular electric quadrupole moment (MEQM) for the set of molecules N2, C2H2, CO, CO2, CS2, HF, and BH. We have used SR-SDCI and (SC)2-SR-SDCI methods and we have compared our results with high-level theoretical ones, including FCI values for HF and BH, and with experimental values. The calculated MEQM provides a test of the effect that the energy converged (SC)2 dressing method brings to the SDCI wavefunctions. The results suggest that the (SC)2-SR-SDCI method can be a cost-effective and quite accurate method for the calculation of post-SCF effects on electric quadrupole moments.