Ion dissolution mechanism and kinetics at kink sites on NaCl surfaces

Mark N. Joswiak, Michael F. Doherty, Baron Peters

Research output: Contribution to journalArticlepeer-review

Abstract

Desolvation barriers are present for solute–solvent exchange events, such as ligand binding to an enzyme active site, during protein folding, and at battery electrodes. For solution-grown crystals, desolvation at kink sites can be the rate-limiting step for growth. However, desolvation and the associated kinetic barriers are poorly understood. In this work, we use rare-event simulation techniques to investigate attachment/detachment events at kink sites of a NaCl crystal in water. We elucidate the desolvation mechanism and present an optimized reaction coordinate, which involves one solute collective variable and one solvent collective variable. The attachment/detachment pathways for Na+ and Cl are qualitatively similar, with quantitative differences that we attribute to different ion sizes and solvent coordination. The attachment barriers primarily result from kink site desolvation, while detachment barriers largely result from breaking ion–crystal bonds. We compute ion detachment rates from kink sites and compare with results from an independent study. We anticipate that the reaction coordinate and desolvation mechanism identified in this work may be applicable to other alkali halides.

Original languageEnglish (US)
Pages (from-to)656-661
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number4
DOIs
StatePublished - Jan 23 2018
Externally publishedYes

Keywords

  • Crystal growth
  • Desolvation
  • Rare events
  • Rate calculations
  • Reaction coordinate

ASJC Scopus subject areas

  • General

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