A ReaxFF force field for sodium intrusion in graphitic cathodes.

Sodium intercalation and adsorption on graphitic carbon plays an important role in cathode wear during aluminium electrolysis and is relevant for sodium ion battery (NIB) applications. We present a parameter set for the ReaxFF formalism trained to describe sodium interactions with graphitic carbon. The force field developed reproduce the training data with reasonable accuracy and displays qualitatively adequate predictive power.

Chemically accurate energy barriers of small gas molecules moving through hexagonal water rings.

We present chemically accurate potential energy curves of CH4, CO2 and H2 moving through hexagonal water rings, calculated by CCSD(T)/aug-cc-pVTZ with counterpoise correction. The barriers are extracted from a potential energy surface obtained by allowing the water ring to expand while the gas molecule diffuses through. State-of-the-art XC-functionals are evaluated against the CCSD(T) potential energy surface.

Potential Energy Surfaces and Charge Transfer of PAH-Sodium-PAH Complexes.

To further understanding of the role of sodium in carbon cathode degradation in Hall-Héroult cells, potential-energy surfaces and charge-transfer curves are presented for finite-size complexes of sodium intercalated between various polycyclic aromatic hydrocarbons. Calculations for lithium and potassium are included to highlight the disparate intercalation behaviour of the alkali metals in graphite intercalation compounds. Static energy barriers from DFT are used to compute macroscopic diffusion coefficients according to transition-state theory.