Electronic spectroscopy of UO22+, NUO+ and NUN: an evaluation of time-dependent density functional theory for actinides

Abstract

The performance of the time-dependent density functional theory (TDDFT) approach has been evaluated for the electronic spectrum of the UO(2)(2+), NUO(+) and NUN molecules. Different exchange-correlation functionals (LDA, PBE, BLYP, B3LYP, PBE0, M06, M06-L, M06-2X, CAM-B3LYP) and the SAOP model potential have been investigated, as has the relative importance of the adiabatic local density approximation (ALDA) to the exchange-correlation kernel. The vertical excitation energies have been compared with reference data obtained using accurate wave-function theory (WFT) methods.

Electronic structure theory of the superheavy elements

“…The CC method is an allorder, size-extensive, systematic and very accurate many-body approach, as has been shown in many benchmark applications of 4-component relativistic CC methods to heavy and super-heavy atoms [103][104][105][106][107][108][109][110][111][112] and molecules [113][114][115][116][117][118][119][120][121][122]. Multireference variants of relativistic 4-component CC methods capable of handling quasidegeneracies, which are important for open-shell heavy atomic and molecular systems, have also been developed in recent years [102][103][104]106,112,113,122].…”

The electronic spectrum of CUONg4 (Ng = Ne, Ar, Kr, Xe): New insights in the interaction of the CUO molecule with noble gas matrices

“…were correlated, which correspond to 11 occupied (22 electrons) and about 350 virtual spinors. This corresponds to slightly larger active spaces with respect to those employed in our earlier work on the UO 2+ 2 , NUN, and NUO + molecules, 18,99 and significantly enlarged the valence active space in comparison with the previous work of Infante and Visscher. 17 A detailed description of the active spaces for each particular molecule is given in the supplementary material.…”

“…To the diminishing electronegativity of N and C with respect to O there corresponds a decreasing HOMO-LUMO gap, as seen in various theoretical studies 13,17 as a marked decrease of ionization potentials and the lowest electronic excitation energies on going from UO 2+ 2 to NUN, NUO + , and up to CUO. 18,19 For CUO in particular, the HOMO has a predominantly U-C bonding character with the U-O bond lying at significantly lower energy. 17 Moreover, a point is reached where low-lying triplet excited states are so close to the groundstate that some theoretical approaches predict them to be the electronic ground-state.…”

Study of Actinides by Relativistic Coupled Cluster Methods

“…This has been shown in many benchmark applications of 4-component relativistic CC methods to atoms [11][12][13][14][15][16][17][18] and molecules [19][20][21][22][23][24][25][26][27][28][29][30][31]. The CC method is an all-order, size-extensive, and systematic many-body approach.…”

“…Later applications addressed UO 2 , UO + 2 [25] and UO 2+ 2 [26], to resolve contradictions between several high-level molecular electronic spectra calculations. Visscher and coworkers used RFSCC and IH-RFSCC in recent benchmark calculations on uranyl-containing molecules [28][29][30].…”