Singlet–triplet energy gap of a diarylnitroxide diradical by an accurate many-body perturbative approach
Abstract
We report on the calculation of the spin–spin coupling term J in a diarylnitroxide diradical system which is a slightly simplified version of a recently synthesized stable species with a triplet ground state. We have applied our complementary space perturbative approach using virtual orbitals appropriately modified with the aim of investigating, through molecular fragmentation, the effects of the non-bridge aryls. We show how by using multireference