Ab initio studies of actinide species

Actinide oxyfluorides: The bonding trends among the naked, triatomic [OAnO]q+ groups or the oxyfluorides [AnOnFm]q with fo configurations are studied by fully relativistic Dirac-Fock and quasirelativistic pseudopotential methods. (For an isoelectronic map of studied systems, see the abstract by P. Pyykkd at 32JA, Fig 1.) The triatomic fo series is suggested to range from the bent ThO2 via the linear OPaO+ to at least NpO23+, a possible new gas-phase species [1]. Several novel actinide oxyfluoride species are predicted. The neutral ones include the experimentally so far unknown NpO2F3 and PuO2F4 [1]. Some experimentally known species such as NpO3F and Pu(VI) oxyfluoride species are characterized for the first time by means of the calculated structure and vibrational spectra. Equatorial bonding: The participation of 5fφ orbital in equatorial bonding of actinyls is studied [1]. For UO2F3 , UO2F42-, NpO2F3, NpO2F42-, and NpO2F52-, the 5fφU-2pF overlap populations are 0.11, 0.03, 0.16, 0.24, and 0.21, respectively. A closer look at the specific molecular orbitals in Figure 1 makes the covalent involvement of the 5fφ in bonding quite evident