Nucleation Projects
Seeding Simulations
We followed growth or dissolution of urea crystal seeds in aqueous solution using molecular dynamics simulations to determine the critical nucleus size and established the dependence of critical size on solution concentration.
We found competing effects on the interfacial energy from increasing curvature of the crystal-solution interface and increasing solution concentration as the critical nucleus size decreased. Current nucleation models do not account for size- and concentration- dependence of the interfacial energy; more realistic nucleation models need to be developed.
We are extending this study to investigate heterogeneous nucleation of urea at a solid surface.
Macleod et al, in preparation
Anker, et al, Crystal Growth and Design, 24, 143-158 (2024)
Interfacial concentration
Nucleation experiments on glycine aqueous solutions found that an oil-solution interface dramatically accelerates glycine nucleation compared to an air-solution interface. Molecular dynamics simulations predicted significantly enhanced glycine concentrations at the oil-solution interface. The interfacial enhancement has been experimentally verified by SPR measurements of glycine solutions at gold and polystyrene surfaces. This interfacial concentration is expected to be present in a wide range of solution systems, and has important implications for heterogeneous nucleation.
Mackay, et al, J. Phys. Chem. Lett. 17, 5535 (2026)
McKechnie, et al. J. Phys. Chem. C 126, 16387 (2022)
McKechnie, et al. J. Phys. Chem. Lett. 11, 2263-2271 (2020)
Catching nucleation in action
We are using SERS to investigate the early stages of nucleation of glycine on gold nanoparticles. DFT simulations were used to predict the vibrational spectra of neutral and zwitterionic glycine on gold, which will help to interpret SERS spectra.
Christie, et al. Vib. Spectrosc., 137, 103783 (2025)
Mohammadpour and Johnston, Comput. Theor. Chem. 1227, 114224 (2023)
Vesga, et al. Colloids and Surfaces A 621, 126523 (2021)
