Electronic structure of AlP3 and AlP3−

Using density functional theory (B3LYP-DFT) and ab initio methods [MP2 and CCSD(T)] with the 6-311+G(2df) one particle basis set, two singlet states (1A1-C2v and 1A′-Cs) are found to be nearly degenerate and lower in energy by at least 0.5 eV than the triplet (3A2-C3v) state previously predicted as the ground electronic state of AlP3. AlP3− has an 2A′-Cs ground state, with low-lying 2A″-Cs,2A1-C3v and 2A1-C2v excited states at 0.04, 0.25, 0.29 eV, respectively. The adiabatic electron affinity of AlP3 is calculated to be 1.9 eV.