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Supporting information to accompany: Super-Ancillary Equations for Cubic Equations of State

Metadata Updated: September 30, 2025

Supplementary files to accompany the the paper "Super-Ancillary Equations for Cubic Equations of State" of Ian Bell and Ulrich Deiters in Ind. Eng. Chem. Res. Abstract: Calculation of thermodynamic phase equilibrium is error-prone and can fail both near the critical point and at very low temperatures due to the limited precision available in double precision arithmetic. Most importantly, these calculations frequently represent a computational bottleneck. In this work we extend the "super-ancillary" equation approach developed for reference multiparameter equations of state to classical cubic equations of state (van der Waals, Redlich-Kwong-Soave, Peng-Robinson). Iterative calculations in double precision are replaced by non-iterative evaluation of pre-built Chebyshev expansions constructed with extended precision arithmetic. Exact solutions for the equation of state constants are given. The Chebyshev expansions are shown to reproduce the equation of state values to within nearly double precision (aside from in the very near vicinity of the critical point) and are more than 40 times faster to evaluate than the VLE calculations from the fastest computational library. In this way we further expand the domains in which iterative calculations for pure fluid phase equilibria may be rendered obsolete. A C++ header implementing these expansions (and with no external dependencies) is provided as supplemental information. Contact Ian Bell (ian.bell@nist.gov) for more information about this paper and/or the supporting information

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Public: This dataset is intended for public access and use. License: See this page for license information.

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Dates

Metadata Created Date September 30, 2025
Metadata Updated Date September 30, 2025
Data Update Frequency irregular

Metadata Source

Harvested from Commerce Non Spatial Data.json Harvest Source

Additional Metadata

Resource Type Dataset
Metadata Created Date September 30, 2025
Metadata Updated Date September 30, 2025
Publisher National Institute of Standards and Technology
Maintainer
Identifier ark:/88434/mds2-2394
Data First Published 2021-04-23
Language en
Data Last Modified 2021-04-14 00:00:00
Category Chemistry:Chemical engineering and processing, Chemistry:Thermochemical properties, Mathematics and Statistics:Numerical methods and software
Public Access Level public
Data Update Frequency irregular
Bureau Code 006:55
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id c209d922-cef6-443a-a53e-62aaa1aed319
Harvest Source Id bce99b55-29c1-47be-b214-b8e71e9180b1
Harvest Source Title Commerce Non Spatial Data.json Harvest Source
Homepage URL https://data.nist.gov/od/id/mds2-2394
License https://www.nist.gov/open/license
Program Code 006:045
Source Datajson Identifier True
Source Hash 4c418f6dbd6c80b02cf487c85ac5d43f3f3f4ad1c32c9803dc54fb2a6f0c8c88
Source Schema Version 1.1

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