ThermoML

ThermoML – An XML-based IUPAC Standard for Thermodynamic Property Data

ThermoML — an XML-based IUPAC Standard for storage and exchange of experimental thermophysical and thermochemical property data, was initially described in [1], and then further updated in [2]. Supporting information for these articles includes several examples illustrating the use of ThermoML to process experimental data for pure compounds, mixtures, and chemical and biochemical reactions as well as the initial ThermoML specification.

ThermoML covers essentially all experimentally determined thermodynamic and transport property data (more than 120 properties) for pure compounds, multicomponent mixtures, and chemical and biochemical reactions (including change-of-state and equilibrium). Although the focus of ThermoML is properties determined by direct experimental measurement, ThermoML does cover key derived property data such as azeotropic properties, Henry’s Law constants, virial coefficients (for pure compounds and mixtures), activities and activity coefficients, fugacities and fugacity coefficients, and standard properties derived from high-precision adiabatic heat-capacity calorimetry.

The ThermoML structure represents a balanced combination of hierarchical and relational elements. The ThermoML schema structure explicitly incorporates structural elements related to basic principles of phenomenological thermodynamics: thermochemical and thermophysical (equilibrium and transport) properties, state variables, system constraints, phases, and units. Meta- and numerical-data records are grouped into ‘nested blocks’ of information corresponding to data sets. The metadata records precede numerical data information, providing a robust foundation for generating ‘header’ records for any relational database where ThermoML-formatted files could be incorporated. The structural features of the ThermoML metadata records ensure unambiguous interpretation of numerical data as well as data-quality control based on the Gibbs Phase Rule.

Development

“ThermoML” is reserved namespace for the ongoing project ‘XML-based IUPAC standard for experimental and critically-evaluated thermodynamic property data storage and capture’ which was developed under the IUPAC project 2002-055-3-024 (M. Frenkel, Task Group Chairman, J.H. Dymond, E. Koenigsberger, K.N. Marsh, S.E. Stein, W.A. Wakeham – members) and later extended under the IUPAC project 2007-039-1-024 (M. Frenkel, Task Group Chairman, P.L. Brown, R.D. Chirico, J.H. Dymond, R.N. Goldberg, A.R.H. Goodwin, H. Heerklotz, E. Koenigsberger, J.E. Ladbury, K.N. Marsh, D.P. Remeta, S.E. Stein, W.A. Wakeham, P A. Williams – members). Both projects were initially conducted as one of the activities of the IUPAC Committee on Printed and Electronic Publications (CPEP), now superseded by the Committee on Publications and Chemical Data Standards (CPCDS).

The framework of ThermoML is described in detail in [3]. Extensions to the ThermoML schema for; the expression of uncertainties are described in [4]; representation of critically evaluated data, predicted data, and Equation Representation [5]; properties of biomaterials [6]; and speciation and complex equilibria [7]. Supporting Information documents for these articles include examples illustrating application of the extensions. As ThermoML evolves, the current ThermoML specfication (schema) can be found at ThermoML.xsd; (last updated 30 Aug 2011).

In case of minor differences between the text describing ThermoML (ThermoML Recommendations 2006 and ThermoML Recommendations 2011) and the ThermoML schema, should always be considered normative.

Usage

Currently, ThermoML is extensively used in the new data delivery process involving major journals in the field such as Journal of Chemical and Engineering Data [8], The Journal of Chemical Thermodynamics [9], Fluid Phase Equilibria [10], Thermochimica Acta [11], and International Journal of Thermophysics [12], as well as computer application development companies, and the Thermodynamics Research Center (TRC) at the National Institute of Standards and Technology. In order to simplify the process of data compilation by the users, the Guided Data Capture software (GDC) has been developed [13]. The current ThermoML schema and a variety of the ThermoML files containing experimental thermodynamic data reported in the publications of the above-mentioned journals can be downloaded from the (TRC ThermoML website). ThermoML files originally formatted in accordance to the ThermoML Recommendations 2006 can automatically be converted to formats corresponding to the ThermoML Recommendations 2011 using the ThermoML Updater software. Software for conversion of ThermoML files into Microsoft Excel (ThermoML Opener) is also freely available.

References

  1. ‘XML-based IUPAC standard for experimental, predicted, and critically evaluated thermodynamic property data storage and capture (ThermoML) (IUPAC Recommendations 2006)’ Pure Appl. Chem.2006, 78, 541-612
  2. ‘Extension of ThermoML: The IUPAC standard for thermodynamic data communications (IUPAC Recommendations 2011)’ Pure Appl. Chem.2011, 83, 1937-1967
  3. ‘ThermoML – an XML-based Approach for Storage and Exchange of Experimental and Critically Evaluated Thermophysical and Thermochemical Property Data. 1. Experimental Data’ by M. Frenkel, R. D. Chirico, V. V. Diky, Q. Dong, S. Frenkel, P. R. Franchois, D. L. Embry, T. L. Teague, K. N. Marsh, and R. C. Wilhoit, Journal of Chemical and Engineering Data 2003, 48, 2-13.
  4. ‘ThermoML – An XML-Based Approach for Storage and Exchange of Experimental and Critically Evaluated Thermophysical and Thermochemical Property Data. 2. Uncertainties’ J. Chem. Eng. Data2003, 48, 1344-1359 & Supporting information.
  5. ‘ThermoML – An XML-Based Approach for Storage and Exchange of Experimental and Critically Evaluated Thermophysical and Thermochemical Property Data. 3. Critically Evaluated Data, Predicted Data, and Equation Representation’ J. Chem. Eng. Data2004, 49, 381-393 & Supporting information.
  6. ‘ThermoML – An XML-Based Approach for Storage and Exchange of Experimental and Critically Evaluated Thermophysical and Thermochemical Property Data. 4. Biomaterials’ J. Chem. Eng. Data2010, 55, 1564-1572 & Supporting information.
  7. ‘ThermoML – an XML-Based Approach for Storage and Exchange of Experimental and Critically Evaluated Thermophysical and Thermochemical Property Data. 5. Speciation and Complex Equilibria’ J. Chem. Eng. Data2011, 56, 307-316 & Supporting information.
  8. Editorial, 2003, 48, 1
  9. Announcement, 2004, 36, iv
  10. Announcement, 2004, 226, v
  11. Announcement, 2004, 421, 241
  12. Announcement, 2005, 26, 307-308
  13. ‘Windows-Based Guided Data Capture Software for Mass-Scale Thermophysical and Thermochemical Property Data Collection’ J. Chem. Inf. Comp. Sci.2003, 43, 15-24