Influence of the Pauli antisymmetry and exclusion principle on the electronic structure of π systems — a combined Green function quantum Monte Carlo and configuration interaction study

Abstract

It is demonstrated that the Pauli antisymmetry principle (PAP) is a hidden variable in π electron calculations of polyenes and annulenes with 4 n + 2 π electrons ( n = 0, 1, 2,...). Here the π electrons behave as a hard core bosonic ensemble which represents a superposition of fermionic on-site and bosonic intersite properties. In 4 n rings ( n = 1, 2,...) the PAP leads to a destabilization of the π electronic system. With an increasing π electron count the Pauli exclusion principle (PEP) raises the normalized π energy of annulenes. The influence of the PEP and PAP on the π electron localization properties is analyzed in terms of charge fluctuations.