Speciation of carbonates in water under pressure: the effect of counterions

We address a problem relevant to the Earth deep carbon cycle: the speciation of carbonates in

water under pressure, as a function of the counterions present in the solution. Experimentally,

it is challenging to characterize the properties of species dissolved in aqueous solutions at

extreme conditions. Here, we adopt a first-principle computational approach, and we study the

speciation of carbonates in the presence of platinum using ab initio molecular dynamics and

the Qbox code (http://qboxcode.org/). We predict the structural and vibrational properties of

carbonates in in the presence of cations (K+, Na+, Ca2+, and Pt2+) and we compare our results

with limited experimental data and with geochemical models. Our study gives insights into the

speciation of platinum in aqueous carbonates which are critical to the understanding of

platinum deposits and ore formation.