Program > Browse abstracts by speaker > Jahn Sandro

Fluids are important transport agents in ore-forming processes. Their ability to carry metal ions depends not only on temperature and pressure but also on the availability of suitable ligands. Fluid speciation is usually derived from solubility experiments or in situ spectroscopic measurements. However, the interpretation of measured data is often not straightforward and sometimes ambiguous. Molecular dynamics (MD) simulations are a powerful complementary approach to study complexation in fluids. In addition to following individual molecular trajectories in real time, the calculation of theoretical spectra, e.g., of vibrational or electronic properties, support the interpretation of experimental data substantially. Advanced sampling methods such as metadynamics allow the determination of stability constants of individual species, which are needed as input parameters for thermodynamic modeling.

Here, we present results from classical and ab initio MD simulations of trivalent (e.g. La, Y) and tetravalent (e.g. Ge, Re) ions in aqueous and carbonatitic fluids up to lower crustal temperatures and pressures. We compare and discuss various computational approaches including simulations with ab initio and classical potentials, or single-phase vs. two phase simulations. Theoretical XANES or vibrational spectra are compared to experimental data from the literature. If time allows, we will also cover the incorporation of those elements into ore minerals and discuss implications for element partitioning between minerals and fluids.

This work has been funded by DFG within Priority Program SPP2238 (grant IDs JA1469/13-1, 17-1 and 18-1). Part of the simulations has been performed on the JUWELS supercomputer at Jülich Supercomputing Centre (JSC) under Gauss Centre for Supercomputing (GCS) projects hydrothermal and hydrothermal2.