Choosing between alternative MP2 algorithms in the self-consistent reaction field theory of solvent effects

The MP2 energy and electronic density can be obtained in the framework of the self-consistent reaction field theory of solvent effects by the simple application of the usual MP2 formulae using SCF orbitals which have been optimized in the self-consistent reaction field of the SCF density. Iterative schemes which apply an MP2-corrected density to achieve self-consistency of the reaction field are not only computationally much longer, but inconsistent, since they involve higher (fourth) order corrections in the electron correlation.