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18.7 CABS Singles correction

By default, the perturbative CABS singles correction as described in J. Chem. Phys. 127, 221106 (2007) and J. Chem. Phys. 128, 154103 (2008) is included in the reference energy of all MP2-F12 and CCSD-F12 calculations (now also in all local F12 calculations). The corrected reference energy is stored in variable ENERGR, so that ENERGY-ENERGR are the total correlation energies.

The singles correction can be turned off by option SINGLES=0, e.g.


The contribution of core orbitals to the singles energy is not included by default, but can be turned on by option CORE_SINGLES, e.g.

MP2-F12,CORE_SINGLES=1 2017-12-16