Interatomic Potentials for Simulating MnO₂ Polymorphs

Abstract

Interatomic potentials for manganese dioxide have been derived via fitting to the structures of the chain MnO₂ polymorphs, pyrolucite and ramsdellite. The quality of the potentials was assessed by using them to simulate the structure of spinel-based λ-MnO₂, which was not part of the fitting set. Lattice parameters of all three structures were reproduced to within 2% of the experimental values. The potentials have also been used to successfully simulate the idealised structures of the MnO₂ polymorphs containing tunnels and suggest that tunnels larger than {\rm 2 \times 3} are not stable  without the presence of additional species within them. The stabilities of the polymorphs have been calculated and, somewhat unexpectedly, the spinel-based structure is found to be less stable  that the tunnel structures.

Keywords:

• Electrolytic manganese dioxide (EMD)
• Polymorphs
• Interatomic Potentials
• Molecular modelling