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Position-Specific and Clumped Stable Isotope Studies: Comparison of the Urey and Path-Integral Approaches for Carbon Dioxide, Nitrous Oxide, Methane, and Propane

Webb, Michael A. and Miller, Thomas F., III (2013) Position-Specific and Clumped Stable Isotope Studies: Comparison of the Urey and Path-Integral Approaches for Carbon Dioxide, Nitrous Oxide, Methane, and Propane. Journal of Physical Chemistry A . ISSN 1089-5639. https://resolver.caltech.edu/CaltechAUTHORS:20140113-090540183

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Abstract

We combine path-integral Monte Carlo methods with high-quality potential energy surfaces to compute equilibrium isotope effects in a variety of systems relevant to ‘clumped’ isotope analysis and isotope geochemistry, including CO_2, N_2O, methane, and propane. Through a systematic study of heavy-atom isotope-exchange reactions, we quantify and analyze errors that arise in the widely used Urey model for predicting equilibrium constants of isotope-exchange reactions using reduced partition function ratios. These results illustrate that the Urey model relies on a nontrivial cancellation of errors that can shift the apparent equilibrium temperature by as much as 35 K for a given distribution of isotopologues. The calculations reported here provide the same level of precision as the best existing analytical instrumentation, resolving the relative enrichment of certain isotopologues to as little as 0.01‰. These findings demonstrate path-integral methods to be a rigorous and viable alternative to more approximate methods for heavy-atom geochemical applications.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/jp411134vDOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp411134vPublisherArticle
ORCID:
AuthorORCID
Webb, Michael A.0000-0002-7420-4474
Miller, Thomas F., III0000-0002-1882-5380
Additional Information:© 2013 American Chemical Society. Received: November 12, 2013; Revised: December 20, 2013; Publication Date (Web): December 27, 2013. This research was supported by the Resnick Sustainability Institute and the Department of Energy (DE-SC0006598). We acknowledge computing resources from the National Energy Research Scientific Computing Center (DE-AC02-05CH11231) and a Director’s Discretionary Allocation from the Argonne Leadership Computing Facility. We thank José Zúñiga and Tim Lee for providing information and subroutines for their potential energy surfaces. We also thank John Eiler, Alex Sessions, and Adam Subhas for helpful discussions.
Group:Resnick Sustainability Institute
Funders:
Funding AgencyGrant Number
Resnick Sustainability InstituteUNSPECIFIED
Department of Energy (DOE)DE-SC0006598
Department of Energy (DOE)DE-AC02-05CH11231
Argonne Leadership Computing FacilityUNSPECIFIED
Record Number:CaltechAUTHORS:20140113-090540183
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140113-090540183
Official Citation:Position-Specific and Clumped Stable Isotope Studies: Comparison of the Urey and Path-Integral Approaches for Carbon Dioxide, Nitrous Oxide, Methane, and Propane Michael A. Webb and Thomas F. Miller, III The Journal of Physical Chemistry A Article ASAP
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43327
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:13 Jan 2014 21:28
Last Modified:03 Oct 2019 06:06

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