Entropy of water calculated from harmonic approximation: estimation of the accuracy of method

Jan Zielkiewicz

doi:10.1063/1.2921161

Entropy of water calculated from harmonic approximation: estimation of the accuracy of method

Abstract

Some molecular dynamics simulations were performed for liquid TIP4P and SPC water at a constant density (1.00 g/cm(3)) and within the temperature range of 5-90 degrees C. By using harmonic approximation, both the entropy of water S-H and the specific heat c(v) were calculated, and the results were compared to literature data. It was found that harmonic approximation overestimates absolute entropy of TIP4P water by 5.6 J/mol K (similar to 9.5%) at 278 K, but only by 0.4 J/mol K (similar to 0.5%) at 363 K. The value of the specific heat, however, is strongly underestimated: for TIP4P and SPC model, we obtain 59.5 and 56.9 J/mol K using harmonic approximation, while the correct values are 79.0 and 72.3 J/mol K, respectively.

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Jan Zielkiewicz prof. dr hab. inż.

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DOI:: Digital Object Identifier (open in new tab) 10.1063/1.2921161
License: Copyright (2008 American Institute of Physics)

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Category:: Articles
Type:: artykuł w czasopiśmie z listy filadelfijskiej
Published in:: JOURNAL OF CHEMICAL PHYSICS no. 128,
ISSN: 0021-9606
Language:: English
Publication year:: 2008
Bibliographic description:: Zielkiewicz J.: Entropy of water calculated from harmonic approximation: estimation of the accuracy of method// JOURNAL OF CHEMICAL PHYSICS. -Vol. 128., nr. iss. 19 (2008),
DOI:: Digital Object Identifier (open in new tab) 10.1063/1.2921161
Verified by:: Gdańsk University of Technology