USE OF CONFIGURATION SELECTION METHODS TO STUDY THE SUDDEN POLARIZATION EFFECT

The variation of the dipole moment of twisted ethylene as a function of the angle of pyramidalization of one CH2 group is determined for a variety of AO basis sets and levels of CI treatment. The results for moderate amounts of pyramidalization are seen to be strongly dependent on the choice of one-electron basis functions in the CI, although for still larger angles (20° and beyond) this effect becomes much less important. Configuration selection methods prove to be very effective in this investigation, making feasible the extension of such calculations to more chemically interesting systems than would otherwise be possible. © 1979, American Chemical Society. All rights reserved.