posted on 2023-12-12, 23:03authored byJan-Niklas Boyn, Emily A. Carter
The
carbonate minerals of Ca and Mg are abundant throughout
the
lithosphere and have recently garnered significant research interest
as possible long-term carbon sinks in the sequestration of atmospheric
carbon dioxide. Nonetheless, an understanding of the atomic-level
processes comprising their mineralization remains limited. Here, we
characterize and contrast the mechanisms of contact ion-pair formation
in aqueous Ca and Mg carbonate systems, which represents the most
fundamental step leading to the formation of their mineral solids.
Utilizing multilevel embedded correlated wavefunction-based ab initio
molecular dynamics/quantum mechanics simulations, we characterize
not only the dynamics of these processes but also factors arising
from the electronic structure of the involved species, revealing further
details of the fundamentally different mechanisms for the interconversion
between the contact ion-pairs and solvent-shared ion-pairs of Ca versus
Mg carbonate.