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Activity–composition relations in the system CaCO3–MgCO3 predicted from static structure energy calculations and Monte Carlo simulations

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Title: Activity–composition relations in the system CaCO3–MgCO3 predicted from static structure energy calculations and Monte Carlo simulations
Authors: Vinograd, Victor L.1 v.vinograd@kristall.uni-frankfurt.de, Burton, Benjamin P.2, Gale, Julian D.3, Allan, Neil L.4, Winkler, Björn1
Source: Geochimica et Cosmochimica Acta. Feb2007, Vol. 71 Issue 4, p974-983. 10p.
Subjects: Monte Carlo method, Mathematical models, Thermodynamics, Physical & theoretical chemistry
Abstract: Abstract: Thermodynamic mixing properties and subsolidus phase relations of the rhombohedral carbonate system, (1− x)·CaCO3 − x ·MgCO3, were modelled in the temperature range of 623–2023K with static structure energy calculations based on well-parameterised empirical interatomic potentials. Relaxed static structure energies of a large set of randomly varied structures in a 4×4×1 supercell of calcite (a =19.952Å, c =17.061Å) were calculated with the General Utility Lattice Program (GULP). These energies were cluster expanded in a basis set of 12 pair-wise effective interactions. Temperature-dependent enthalpies of mixing were calculated by the Monte Carlo method. Free energies of mixing were obtained by thermodynamic integration of the Monte Carlo results. The calculated phase diagram is in good agreement with experimental phase boundaries. [Copyright &y& Elsevier]
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Database: Engineering Source
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Abstract:Abstract: Thermodynamic mixing properties and subsolidus phase relations of the rhombohedral carbonate system, (1− x)·CaCO3 − x ·MgCO3, were modelled in the temperature range of 623–2023K with static structure energy calculations based on well-parameterised empirical interatomic potentials. Relaxed static structure energies of a large set of randomly varied structures in a 4×4×1 supercell of calcite (a =19.952Å, c =17.061Å) were calculated with the General Utility Lattice Program (GULP). These energies were cluster expanded in a basis set of 12 pair-wise effective interactions. Temperature-dependent enthalpies of mixing were calculated by the Monte Carlo method. Free energies of mixing were obtained by thermodynamic integration of the Monte Carlo results. The calculated phase diagram is in good agreement with experimental phase boundaries. [Copyright &y& Elsevier]
ISSN:00167037
DOI:10.1016/j.gca.2006.11.008