Machine Learning-Assisted Hybrid ReaxFF Simulations.

We have developed a machine learning (ML)-assisted Hybrid ReaxFF simulation method ("Hybrid/Reax"), which alternates reactive and non-reactive molecular dynamics simulations with the assistance of ML models to simulate phenomena that require longer time scales and/or larger systems than are typically accessible to ReaxFF. Hybrid/Reax uses a specialized tracking tool during the reactive simulations to further accelerate chemical reactions. Non-reactive simulations are used to equilibrate the system after the reactive simulation stage.

Microdroplet Fusion Chemistry for Charge State Reduction of Synthetic Polymers via Bipolar Dual Spray with Anionic Reagents.

Microdroplet fusion chemistry is an emerging area of analyte manipulation that utilizes the ion source region of a mass spectrometer to covalently derivatize or manipulate the charge state distribution. This technique utilizes two electrospray emitters in close proximity, where the droplets from each electrospray plume fuse and undergo the subsequent chemistry. In this study, microdroplet fusion chemistry via bipolar dual spray has demonstrated the ability to reduce the average charge state of polyethylene glycol (PEG) cations using anionic reagents.

Spin accommodation and reactivity of aluminum based clusters with O2.

It is shown that spin accommodation plays a determining role in the reactivity of aluminum based anion clusters with oxygen. Experimental reactivity studies on aluminum and aluminum-hydrogen clusters show variable reactivity in even electron systems and rapid etching in odd electron systems. The reactivity of even electron clusters is governed by a spin transfer to the singlet cluster through filling of the spin down antibonding orbitals on triplet oxygen.