Quantum Chemical Calculations
Quantum chemical calculations (mainly the DFT calculations) are used for tackling various scientific problems related with Resource Ecology.
Structures of actinide complexes
Density functional theory calculations are used to obtain the structures of various actinide complexes in aqueous solution. EXAFS spectroscopy is generally a well-suited tool to characterize the structures of actinide complexes (Molecular Structures Division). Here, DFT calculations are used as a complementary tool for EXAFS spectroscopy in order to deduce 3D structural information of actinide complexes. The calculated and experimental bond distances agree well within the accuracy of ± 0.02 Å and show the validity of combination of two approaches.
Characterization of metal-ligand binding
Infrared absorption spectroscopy (IR) is a conventional and well-established technique for characterization of ligand binding to metals. Using FT-IR spectroscopy, tracer level concentration of metal coordination complexes are detected and they have been characterized (Biophysics Division, Surface Processes Division). However often difficulties arise how to interpret the measured spectra, especially when the spectra contains manifold of absorption bands. This is often the case in organometallic complexes. DFT and MP2 calculations are used here to assist the interpretation of the experimentally obtained spectra.
The presence of 5f electrons makes the unique character of actinide series yet the role of 5f electrons in the bonding between actinide and ligand is not fully understood. Quantum chemical calculations are used to understand more about the chemical bonds in actinide complexes.
Photochemistry and luminescence
Photochemistry and luminescence of uranium(VI) are explored by DFT calculations as well as using experimental techniques (Biogeochemistry Division, Biophysics Division, Institute of Radiation Physics). The lowest-lying triplet states of uranium(VI) complexes obtained by DFT calculations are found to be largely correlated with their photochemical and luminescence characters. Quenching of uranium(VI) luminescence by various ions and molecules are studied and the mechanisms of quenching have been identified. Luminescence properties of lanthanide-doped silicates are also studied using time-dependent DFT (TD-DFT) and CAS-SCF theories where corresponding information are provided from experiments (Institute of Ion Beam Physics and Materials Research).
Metal sorption on surfaces
Sorption is one of the most important process that governs the metal transport in geological media. DFT calculations are used to study the sorption of metal cations and anions on the surface of minerals. Corresponding information is provided by EXAFS and FT-IR spectroscopy (Molecular Structures Division, Surface Processes Division).