Obtaining Consistent Free Energies for Ion Binding at Surfaces from Solution: Pathways versus Alchemy for Determining Kink Site Stability
Ion incorporation or removal from a solid at the interface with solution is a fundamental part of crystal growth. Despite this, there have been few quantitative determinations of the thermodynamics for such processes from atomistic molecular dynamics due to the associated technical challenges. In th...
| Main Authors: | , , |
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| Format: | Journal Article |
| Language: | English |
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AMER CHEMICAL SOC
2022
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| Subjects: | |
| Online Access: | http://hdl.handle.net/20.500.11937/97832 |
| _version_ | 1848766327738597376 |
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| author | Silvestri, A. Raiteri, Paolo Gale, Julian |
| author_facet | Silvestri, A. Raiteri, Paolo Gale, Julian |
| author_sort | Silvestri, A. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Ion incorporation or removal from a solid at the interface with solution is a fundamental part of crystal growth. Despite this, there have been few quantitative determinations of the thermodynamics for such processes from atomistic molecular dynamics due to the associated technical challenges. In this study, we compute the free energies for ion removal from kink sites at the interface between NaCl and water as an illustrative example. To examine the influence of the free energy technique used, we compare methods that follow an explicit pathway for dissolution with those that focus on the thermodynamics of the initial and final states using metadynamics and free energy perturbation, respectively. While the initial results of the two approaches are found to be completely different, it is demonstrated that the thermodynamics can be reconciled with appropriate corrections for the standard states, thus illustrating the need for caution in interpreting raw free energy curves for ion binding as widely found in the literature. In addition, a new efficient approach is introduced to correct for the system size dependence of kink site energies both due to the periodic interaction of charges in an inhomogeneous dielectric system and due to the dipolar interactions between pairs of kinks along a row. Ultimately, it is shown that with suitable care, both classes of free energy techniques are capable of producing kink site stabilities that are consistent with the solubility of the underlying bulk solid. However, the precise values for individual kink sites exhibit a small systematic offset, which can be ascribed to the contribution of the interfacial potential to the pathway-based results. For the case of NaCl, the free energies of the kink sites relative to a 1 M aqueous solution for Na+and Cl-are found to be surprisingly different and of opposite sign, despite the ions having very similar hydration free energies. |
| first_indexed | 2025-11-14T11:49:23Z |
| format | Journal Article |
| id | curtin-20.500.11937-97832 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:49:23Z |
| publishDate | 2022 |
| publisher | AMER CHEMICAL SOC |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-978322025-07-22T07:07:24Z Obtaining Consistent Free Energies for Ion Binding at Surfaces from Solution: Pathways versus Alchemy for Determining Kink Site Stability Silvestri, A. Raiteri, Paolo Gale, Julian Science & Technology Physical Sciences Chemistry, Physical Physics, Atomic, Molecular & Chemical Chemistry Physics METAL-IONS DISSOLUTION WATER SIMULATIONS NACL GROWTH PREDICTION MECHANISM CONSTANT CRYSTALS Alchemy Ions Sodium Chloride Thermodynamics Water Sodium Chloride Ions Water Thermodynamics Alchemy Ion incorporation or removal from a solid at the interface with solution is a fundamental part of crystal growth. Despite this, there have been few quantitative determinations of the thermodynamics for such processes from atomistic molecular dynamics due to the associated technical challenges. In this study, we compute the free energies for ion removal from kink sites at the interface between NaCl and water as an illustrative example. To examine the influence of the free energy technique used, we compare methods that follow an explicit pathway for dissolution with those that focus on the thermodynamics of the initial and final states using metadynamics and free energy perturbation, respectively. While the initial results of the two approaches are found to be completely different, it is demonstrated that the thermodynamics can be reconciled with appropriate corrections for the standard states, thus illustrating the need for caution in interpreting raw free energy curves for ion binding as widely found in the literature. In addition, a new efficient approach is introduced to correct for the system size dependence of kink site energies both due to the periodic interaction of charges in an inhomogeneous dielectric system and due to the dipolar interactions between pairs of kinks along a row. Ultimately, it is shown that with suitable care, both classes of free energy techniques are capable of producing kink site stabilities that are consistent with the solubility of the underlying bulk solid. However, the precise values for individual kink sites exhibit a small systematic offset, which can be ascribed to the contribution of the interfacial potential to the pathway-based results. For the case of NaCl, the free energies of the kink sites relative to a 1 M aqueous solution for Na+and Cl-are found to be surprisingly different and of opposite sign, despite the ions having very similar hydration free energies. 2022 Journal Article http://hdl.handle.net/20.500.11937/97832 10.1021/acs.jctc.2c00787 English AMER CHEMICAL SOC fulltext |
| spellingShingle | Science & Technology Physical Sciences Chemistry, Physical Physics, Atomic, Molecular & Chemical Chemistry Physics METAL-IONS DISSOLUTION WATER SIMULATIONS NACL GROWTH PREDICTION MECHANISM CONSTANT CRYSTALS Alchemy Ions Sodium Chloride Thermodynamics Water Sodium Chloride Ions Water Thermodynamics Alchemy Silvestri, A. Raiteri, Paolo Gale, Julian Obtaining Consistent Free Energies for Ion Binding at Surfaces from Solution: Pathways versus Alchemy for Determining Kink Site Stability |
| title | Obtaining Consistent Free Energies for Ion Binding at Surfaces from Solution: Pathways versus Alchemy for Determining Kink Site Stability |
| title_full | Obtaining Consistent Free Energies for Ion Binding at Surfaces from Solution: Pathways versus Alchemy for Determining Kink Site Stability |
| title_fullStr | Obtaining Consistent Free Energies for Ion Binding at Surfaces from Solution: Pathways versus Alchemy for Determining Kink Site Stability |
| title_full_unstemmed | Obtaining Consistent Free Energies for Ion Binding at Surfaces from Solution: Pathways versus Alchemy for Determining Kink Site Stability |
| title_short | Obtaining Consistent Free Energies for Ion Binding at Surfaces from Solution: Pathways versus Alchemy for Determining Kink Site Stability |
| title_sort | obtaining consistent free energies for ion binding at surfaces from solution: pathways versus alchemy for determining kink site stability |
| topic | Science & Technology Physical Sciences Chemistry, Physical Physics, Atomic, Molecular & Chemical Chemistry Physics METAL-IONS DISSOLUTION WATER SIMULATIONS NACL GROWTH PREDICTION MECHANISM CONSTANT CRYSTALS Alchemy Ions Sodium Chloride Thermodynamics Water Sodium Chloride Ions Water Thermodynamics Alchemy |
| url | http://hdl.handle.net/20.500.11937/97832 |