Development of a force field for modeling lithium borosilicate glasses

Abstract A force field (FF) with a Buckingham function was developed for modeling lithium borosilicate (LBS) glasses using molecular dynamics (MD) simulations. The parameter set of the FF for two‐body interaction between Li and O (Li–O) was optimized to reproduce both theoretically calculated force and energy using the density functional theory (DFT) and experimental properties, such as density and mechanical moduli. Bayesian optimization based on a machine‐learning technique was employed to efficiently find the best parameter set in a wide parameter space. The accuracy of the MD simulation using the optimized FF of Li–O together with the previously reported FFs for Si–O, B–O, and O–O pairs was examined by comparing with experimentally measured boron coordination numbers () in a variety of LBS glasses. Consequently, it was found that the combination of the FFs is not accurate enough to reproduce the boron coordination change with varying glass compositions. Therefore, the parameter set of the B–O pair was extended to be composition‐dependent to reproduce the experimental data on the N. It was confirmed that the empirical parameter correction as a function of [SiO]/[BO] and [LiO]/[BO] ratios enables modeling LBS glass consistently with experimental NMR data.