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 th e simple application of the usual MP2 formulae using SCF orbitals whic h have been optimized in the self-consistent reaction field of the SCF density. Iterative schemes which apply an MP2-corrected density to ac hieve self-consistency of the reaction field are not only computationa lly much longer, but inconsistent, since they involve higher (fourth) order corrections in the electron correlation.