Alkali hydroxide (LiOH, NaOH, KOH) in water: Structural and vibrational properties, including neutron scattering results

Structural and vibrational properties of aqueous solutions of alkali hydroxides (LiOH, NaOH, and KOH) are computed using quantum molecular dynamics simulations for a range of solute concentration between 1 and 10 M. Element-resolved partial radial distribution functions, neutron and X-ray structure factors, and angular distribution functions are computed for the three hydroxide solutions as a function of concentration. Vibrational spectra and frequency dependent conductivity are computed from the Fourier transforms of velocity autocorrelation and current autocorrelation functions. Our results for the structure are validated with the available neutron data for 17 M concentration of NaOH in water. We found that the larger ionic radius () and higher concentration disturb the hydrogen-bond network of water, resulting in more disordered cationic hydration shell. Our ab initio simulation data for a range of solute concentration between 1 and 10 M can be used to guide future elastic and inelastic neutron-scattering experiments.

Acknowledgments: This research was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, Neutron Scattering and Instrumentation Sciences program under Award DE‐SC0023146.