title: Understanding hydration of Zn2+ in hydrothermal fluids with ab initio molecular dynamics.
abstract: With ab initio molecular dynamics simulations, the free-energy profiles of hydrated Zn(2+) are calculated for both gaseous and aqueous systems from ambient to supercritical conditions, and from the derived free-energy information, the speciation of hydrated Zn(2+) has been revealed. It is shown that the 4, 5 and 6 fold complexes coexist in both phases at ambient condition. As T-P increases a clear trend is found for both phases: the 6 fold states gradually become unstable and cannot exist stably any more over 620 K, but in contrast, the 4 and 5 fold states can hold up to 1000 K with similar probabilities. It is found that the stability of the 4 and 5 fold states has an entropic origin. This study constitutes a relatively complete speciation picture for aqua-zinc complexes over a broad T-P range.
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, PR China. xiandongliu@nju.edu.cn
authors.forename: Xiandong
authors.initials: X
authors.lastname: Liu
authors.forename: Xiancai
authors.initials: X
authors.lastname: Lu
authors.forename: Rucheng
authors.initials: R
authors.lastname: Wang
authors.forename: Evert Jan
authors.initials: EJ
authors.lastname: Meijer