title: 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 CI techniques it is now possible to obtain accurate and reliable values of J even for large organic radicals, the basic units of longer chain polyradical systems.
authors.affiliation: Scuola Normale Superiore, Piazza dei Cavalieri, I-56126 Pisa, Italy. vincenzo.barone@sns.it
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Barone
authors.forename: Ivo
authors.initials: I
authors.lastname: Cacelli
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ferretti
authors.forename: Susanna
authors.initials: S
authors.lastname: Monti
authors.forename: Giacomo
authors.initials: G
authors.lastname: Prampolini