CYCLOPROPENYL CATION: A PROTOTYPE AROMATIC SYSTEM

Abstract

The cyclopropenyl cation is the simplest member of the $(4n \ + \ 2) \Pi -$electron H\""{u}ckel aromatic series. Therefore, it provides an economical case on which to test computational procedures that might be applied to cyclic $\Pi$-electron systems. Self-consistent field and configuration interaction wavefunctions are used to calculate the ground state and some lowlying excited state energies of the $C_{3}H_{3} ^{+}$ system. The effects of polarization end diffuse basis functions in conjunction with various prescriptions for defining the CI wavefunctions are studied. A comparison among these prescriptions can provide a means to judge the approximations necessary to treat larger aroamatic systems.