Neural network interatomic potentials for kaolin minerals

These results show the accuracy of the created MLIPs to the reference DFT potential, allowing for them to be employed as surrogate DFT interatomic potentials for future work. Through comparison of the computed properties, the need for an accurate description of dispersion interactions when considering these minerals is reinforced. It is also found that, depending on the level of theory desired when studying these systems, different dispersion interactions are better suited to compute specific structural and dynamical properties of the minerals.

In addition, as hydrogen bonding is the predominant interlayer interaction within kaolin minerals, quantum mechanics in the form of nuclear quantum effects (NQEs) are included through the use of path integral molecular dynamics (PIMD) simulations of the main polymorph, kaolinite. These results show the small, but nonnegligible effects of NQEs when considering properties that involve the interlayer 3region of these minerals.

In all presented cases, NQEs are of less importance than an accurate description of dispersion interactions on the structural properties of the mineral, but do weaken the interlayer hydrogen bonds and lower the cohesion of the individual mineral layers to one another. Dynamical properties are much more acutely affected by the explicit consideration of NQEs as observed when considering the O–H regions of computed vibrational spectra to be substantially shifted.