First Principles Simulations of Ions in Water at Ambient and Extreme Conditions

Viktor Rozsa, University of Chicago

Photo of Viktor Rozsa

The interaction of water and ions at high pressure and temperature is crucial to understanding bonding, transport and stability of phases and volatiles within the Earth and other planets. Concurrently, the interaction of water and ions under nanoconfinement is critical to the engineering of novel energy and environmental technologies, including battery and photoelectrochemical cell design. Here, we aim to study both extreme thermodynamic and nanoconfined conditions by examining the solvation properties of ions in water using first-principles simulation. We computed ab initio molecular dynamics trajectories of various monovalent cations in water at ambient conditions. The simulations include multiple independent trajectories with total simulation time of about 0.5 ns/cation, allowing statistically robust comparisons of self-diffusion of ions and water, solvation shell properties, and the local and global effects of ions on the structure and dynamics of liquid water. The results at ambient conditions are used as a basis of comparison for preliminary results on aqueous solutions confined within carbon nanotubes as well as aqueous solutions under high pressure and temperature. We compare structure, solvation properties, diffusion and uniquely quantum properties, including Raman/IR spectroscopies and ionic conductivity.

Abstract Author(s): Viktor Rozsa, Tuan Anh Pham, Eric Schwegler, Giulia Galli