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Title: The Critical Role of Anharmonicity in Aqueous Ionic Clusters Relevant to Nucleation

Abstract

Calculating accurate free energies of aqueous ionic clusters is important in many areas of chemical physics. A common practice used in ab initio and other methods to determine the cluster free energy is to use a single energetically favorable configuration and then assume the harmonic approximation. In the present study, we compare and contrast harmonic free energies to those determined from anharmonic configurational sampling and how both compare to experiment. It is found that anharmoncity plays a critical role in determining accurate free energies for the clusters underlying ion-induced nucleation. Consequently, energies, geometries, and frequencies obtained using a single or multiple configurations within the harmonic approximation lead to incorrect aqueous cluster thermodynamics.This work was supported by the Office of Basic Energy Sciences of the Department of Energy, in part by the Chemical Sciences Program. The Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
985056
Report Number(s):
PNNL-SA-52117
Journal ID: ISSN 1932-7447; ISSN 1932-7455; KC0301020; TRN: US201016%%1745
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry C, 111(13):4977-4983; Journal Volume: 111; Journal Issue: 13
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; APPROXIMATIONS; CHEMICAL PHYSICS; CONFIGURATION; FREE ENERGY; HARMONICS; NUCLEATION; SAMPLING; THERMODYNAMICS

Citation Formats

Kathmann, Shawn M., Schenter, Gregory K., and Garrett, Bruce C.. The Critical Role of Anharmonicity in Aqueous Ionic Clusters Relevant to Nucleation. United States: N. p., 2007. Web. doi:10.1021/jp067468u.
Kathmann, Shawn M., Schenter, Gregory K., & Garrett, Bruce C.. The Critical Role of Anharmonicity in Aqueous Ionic Clusters Relevant to Nucleation. United States. doi:10.1021/jp067468u.
Kathmann, Shawn M., Schenter, Gregory K., and Garrett, Bruce C.. Thu . "The Critical Role of Anharmonicity in Aqueous Ionic Clusters Relevant to Nucleation". United States. doi:10.1021/jp067468u.
@article{osti_985056,
title = {The Critical Role of Anharmonicity in Aqueous Ionic Clusters Relevant to Nucleation},
author = {Kathmann, Shawn M. and Schenter, Gregory K. and Garrett, Bruce C.},
abstractNote = {Calculating accurate free energies of aqueous ionic clusters is important in many areas of chemical physics. A common practice used in ab initio and other methods to determine the cluster free energy is to use a single energetically favorable configuration and then assume the harmonic approximation. In the present study, we compare and contrast harmonic free energies to those determined from anharmonic configurational sampling and how both compare to experiment. It is found that anharmoncity plays a critical role in determining accurate free energies for the clusters underlying ion-induced nucleation. Consequently, energies, geometries, and frequencies obtained using a single or multiple configurations within the harmonic approximation lead to incorrect aqueous cluster thermodynamics.This work was supported by the Office of Basic Energy Sciences of the Department of Energy, in part by the Chemical Sciences Program. The Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.},
doi = {10.1021/jp067468u},
journal = {Journal of Physical Chemistry C, 111(13):4977-4983},
number = 13,
volume = 111,
place = {United States},
year = {Thu Apr 05 00:00:00 EDT 2007},
month = {Thu Apr 05 00:00:00 EDT 2007}
}