Gold solubility in alkaline and ammonia-rich hydrothermal fluids: Insights from ab initio molecular dynamics simulations

The role of sulfur in molybdenum transport in hydrothermal fluids: Insight from in situ synchrotron XAS experiments and molecular dynamics simulations

“…The radial distribution functions (RDF) and the coordination number (integrals of RDF) were calculated using VMD (Humphrey et al, 1996) to extract the averaged structural information and to compare with the XAS data. As discussed previously (e.g., Mei et al, 2020), ab initio MD simulations are computationally intensive. Ab initio MD studies published by researchers from various groups (Jahn and Schmidt, 2010;Sulpizi et al, 2013;Liu et al, 2013a, b;Wagner et al, 2017;Stefanski and Jahn 2020) indicate that it is viable to represent the geometrical and thermodynamic properties of solute and solvent molecules within manageable simulation times of tens of picoseconds.…”

“…Our previous studies show that in the MD simulations on the scale of picoseconds, it is difficult to observe simple ligand exchange between ions with charge of -1 such as Cl -, HSand OHdue to the slow exchange kinetics even at elevated temperatures (Mei et al 2015(Mei et al , 2016(Mei et al , 2020.…”

Preface to Multiscale Simulation in Geochemistry

“…The emerging use of machine-learning methods was also illustrated in two contributions that parameterize atomic scale simulations, and upscale geomaterials microscopic properties to continuum-scale modeling. Finally, the topics explored in these contributions span a wide range of geochemical topics applicable to environments from the Earth's core to its surface, including: solid-liquid partitioning under Earth's core conditions (Zhang et al, 2020b), chemical geodynamics of the mantle (Zhang and Liu, 2020), recycling of noble gas in the subduction zones (Wang et al, 2020), thermodynamics of hydrothermal fluids (Mei et al, 2020), interfacial and structural properties of clay and (Fe, Mn) oxide materials (Bylaska et al, 2020;Newton and Kwon, 2020;Zhang et al, 2020a), and a machine learning-based framework for coupling and upscaling of reactive transport processes and parameters across spatial scales (Prasianakis et al, 2020). These papers are briefly introduced in the following.…”

“…The knowledge of thermodynamic properties for aqueous gold complexes is crucial for the understanding of the formation of hydrothermal gold deposits. Mei et al (2020) extrapolated the formation constants of Au + -OH -/NH 3 /H 2 O complexes computed with first principles molecular dynamics (FPMD) simulations to a wide T-P range. Then, these thermodynamic data were used assess the contribution of Au(I)-NH 3 complexes to the solubility of gold in hydrothermal fluids.…”

Molecular Dynamics Simulations of Hot Fluids: From Speciation to Thermodynamics

“…The predicted thermodynamic properties can be extrapolated to a wide range of T-P and incorporated into geochemical modelling software. In the past years, we have employed ab initio MD to refine thermodynamic properties of Cu-Cl/HS [1] , Zn-Cl/HS [2,3] , Pd-Cl/HS [4] , HCl [5] , and create new properties for Au-NH 3 /OH [6] and W-F complexes. The MD-based thermodynamic properties have been successfully applied in geochemical models of ore-forming processes [7] .…”