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Title: Utility of chemical computations in predicting solution free energies of metal ions

Abstract

In this paper, we study quasi-chemical theory (QCT) for the free energies of divalent alkaline earth ions (Ba2+, Sr2+, Ca2+, Mg2+) in water, emphasizing that: (a) interactions between metal ions and proximal water molecules are as strong as traditional chemical effects; (b) QCT builds directly from accessible electronic structure calculations but rests on fully elaborated molecular statistical thermodynamics; (c) QCT offers choices of convenience in identifying coordination numbers for analysis. We investigate utilisation of direct QCT with inner-shell conditioning n λ=$$\overline{n}$$, alternative to the traditional n λ=0 conditioning motivated by a generalised van der Waals view. The alternative n λ=$$\overline{n}$$ works well: deleterious non-Gaussian effects of van der Waals repulsive interactions are not serious, and the alternative conditioning improves the convenience of QCT calculations. Additionally, comparison between ab initio and force field molecular dynamics (AIMD and FFMD) with standard models suggests that FFMD likely exaggerates the anharmonicity in the thermal motion of inner-shell ion-water clusters. Together with the general encouraging support for the harmonic approximations implied by the n λ=$$\overline{n}$$ conditioning, that observation helps explain the remarkable success of the cluster-based QCT solution free energies, which do not require assessment of all inner-shell occupancies by simulation.

Authors:
 [1];  [2];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Tulane Univ., New Orleans, LA (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1485840
Report Number(s):
SAND-2018-11510J
Journal ID: ISSN 0892-7022; 669384
Grant/Contract Number:  
AC04-94AL85000; AC02-05CH11231; AC52-06NA25396
Resource Type:
Accepted Manuscript
Journal Name:
Molecular Simulation
Additional Journal Information:
Journal Volume: 44; Journal Issue: 2; Journal ID: ISSN 0892-7022
Publisher:
Taylor & Francis
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Quasi-chemical theory; ion solvation; ion channel blockers

Citation Formats

Chaudhari, Mangesh I., Pratt, Lawrence R., and Rempe, Susan B. Utility of chemical computations in predicting solution free energies of metal ions. United States: N. p., 2017. Web. doi:10.1080/08927022.2017.1342127.
Chaudhari, Mangesh I., Pratt, Lawrence R., & Rempe, Susan B. Utility of chemical computations in predicting solution free energies of metal ions. United States. doi:10.1080/08927022.2017.1342127.
Chaudhari, Mangesh I., Pratt, Lawrence R., and Rempe, Susan B. Sun . "Utility of chemical computations in predicting solution free energies of metal ions". United States. doi:10.1080/08927022.2017.1342127. https://www.osti.gov/servlets/purl/1485840.
@article{osti_1485840,
title = {Utility of chemical computations in predicting solution free energies of metal ions},
author = {Chaudhari, Mangesh I. and Pratt, Lawrence R. and Rempe, Susan B.},
abstractNote = {In this paper, we study quasi-chemical theory (QCT) for the free energies of divalent alkaline earth ions (Ba2+, Sr2+, Ca2+, Mg2+) in water, emphasizing that: (a) interactions between metal ions and proximal water molecules are as strong as traditional chemical effects; (b) QCT builds directly from accessible electronic structure calculations but rests on fully elaborated molecular statistical thermodynamics; (c) QCT offers choices of convenience in identifying coordination numbers for analysis. We investigate utilisation of direct QCT with inner-shell conditioning nλ=$\overline{n}$, alternative to the traditional nλ=0 conditioning motivated by a generalised van der Waals view. The alternative nλ=$\overline{n}$ works well: deleterious non-Gaussian effects of van der Waals repulsive interactions are not serious, and the alternative conditioning improves the convenience of QCT calculations. Additionally, comparison between ab initio and force field molecular dynamics (AIMD and FFMD) with standard models suggests that FFMD likely exaggerates the anharmonicity in the thermal motion of inner-shell ion-water clusters. Together with the general encouraging support for the harmonic approximations implied by the nλ=$\overline{n}$ conditioning, that observation helps explain the remarkable success of the cluster-based QCT solution free energies, which do not require assessment of all inner-shell occupancies by simulation.},
doi = {10.1080/08927022.2017.1342127},
journal = {Molecular Simulation},
number = 2,
volume = 44,
place = {United States},
year = {2017},
month = {6}
}

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Works referenced in this record:

Projector augmented-wave method
journal, December 1994


Ab initiomolecular dynamics for liquid metals
journal, January 1993