title: Electronic and ionization spectra of 1,1-diamino-2,2-dinitroethylene, FOX-7.
abstract: Singlet, triplet and ionized states of the energetic molecule 1,1-diamino-2,2-dinitroethylene, known as FOX-7 or DADNE, were investigated using the symmetry-adapted-cluster configuration interaction (SAC-CI) ab initio wave function. The 20 computed singlet transitions, with 2 exceptions, were bright. The most intense singlet transitions were of the n₀→π type-typical of molecules having nitro groups. Fast intersystem crossing (ISC) from the 1¹A, 2¹A and 8¹A bright singlet transitions is possible. Other feasible ISC processes are discussed. The computed singlet and ionization spectra have similar features when compared to nitramide and N,N-dimethylnitramine molecules, which have only a nitro group. The ionization energies of the first 20 states have differences in comparison with Koopmans' energy values that can reach 3 eV. Moreover, the character of the first ionized states, dominated by single ionizations, is not the same when compared with the character resulting from application of Koopmans' theorem.
authors.affiliation: Departamento de Química, Instituto Militar de Engenharia, Praça General Tibúrcio, 80, 22290-270, Rio de Janeiro, Brazil, itamar@ime.eb.br.
authors.forename: Itamar
authors.initials: I
authors.lastname: Borges
mesh_terms: D055598:Chemical Phenomena; D003198:Computer Simulation; D004583:Electrons; D005030:Ethylenes / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D009574:Nitro Compounds / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: C520681:1,1-diamino-2,2-dinitroethylene; D005030:Ethylenes; D009574:Nitro Compounds