Structural Characteristics Population Analysis andBinding Energies of An(NO3)2+ (with An = Acto Lr)

摘要

Efficient predictive capabilities are essential for the actinide series since regulatory constraints for radioactive work, associated costs needed for specialized facilities, and the short half-lives of many actinides present great challenges in laboratory settings. Improved predictive accuracy is advantageous for numerous applications including the optimization and design of separation agents for nuclear fuel and waste. One limitation of calculations in support of these applications is that the large variations observed from predictions obtained with currently available methods can make comparisons across studies uncertain. Benchmarking currently available computational methodologies is essential to establish reliable practices across the community to guarantee an accurate physical description of the systems studied. To understand the performance of a variety of common theoretical methods, a systematic analysis of differences observed in the prediction of structural characteristics, electron withdrawing effects, and binding energies of [An(NO3)]²⁺ (with An = Ac to Lr) in gas and aqueous phases is reported. Populationanalysis obtained with Mulliken and Löwdin reflect a largedependence on the level of theory of choice, whereas those obtainedwith natural bond orbital show larger consistency across methodologies.Predicted stability across the actinide series calculated with coupledcluster with perturbative doubles and triples at the triple ζlevel is equivalent to the one obtained when extrapolated to the completebasis set limit. The ground state of [Fm(NO3)]²⁺ and [Md(NO3)]²⁺ is predicted to have an electronicstructure corresponding to An III state in gas and An IV in aqueousphase, whereas the ground state of [An(NO3)]²⁺ (with An = Ac to Es, Lr) presents an electronic structure correspondingto An IV in the gas and aqueous phase. The compounds studied withNo in gas and aqueous phase present a preferred No III state, andthe Lr compounds did not follow trends predicted for the rest of theactinide series, as previously observed in studies regarding its unusualelectronic structure relative to its position in the periodic table.