Wavefunction methods for X-ray scattering
X-ray spectroscopy is an element-specific probe that can be used to study transition-metal enzymes and solution catalysts. With new experimental capabilities, it is now possible to collect high-resolution spectral data that directly probe electronic structure. This makes it important to use theoretical methods that include the important spectral effects. We have recently developed a method, based on multiconfigurational wavefunction theory, to calculate metal K pre-edge spectra of open-shell systems. This also makes it possible to describe X-ray scattering processes using hard X-rays. In addition, the density-matrix renormalization group has recently been implemented for larger calculations, which should significantly expand the range of systems that can be studied. Based on these two developments, we plan to simulate X-rat spectra of a range of different iron and manganese systems in homogenous and enzymatic catalysis. With the recent installation of parallel Molcas we can also start to use Triolith resources more effectively as the serial calculations had severe problems due to the wall-clock time limit for individual jobs.