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Title: Diffusive and quantum effects of water properties in different states of matter

Abstract

The enthalpy, entropy, and free energy of water are important physical quantities for understanding many interesting phenomena in biological systems. However, conventional approaches require different treatments to incorporate quantum and diffusive effects of water in different states of matter. In this work, we demonstrate the use of the two-phase thermodynamic (2PT) model as a unified approach to obtain the properties of water over the whole phase region of water from short (∼20 ps) classical molecular dynamics trajectories. The 2PT model provides an effective way to separate the diffusive modes (gas-like component) from the harmonic vibrational modes (solid-like component) in the vibrational density of states (DoS). Therefore, both diffusive and quantum effect can be properly accounted for water by applying suitable statistical mechanical weighting functions to the DoS components. We applied the 2PT model to systematically examine the enthalpy, entropy, and their temperature dependence of five commonly used rigid water models. The 2PT results are found to be consistent with those obtained from more sophisticated calculations. While the thermodynamic properties determined from different water models are largely similar, the phase boundary determined from the equality of free energy is very sensitive to the small inaccuracy in the values of enthalpy and absolutemore » entropy. The enthalpy, entropy, and diffusivity of water are strongly interrelated, which challenge further improvement of rigid water model via parameter fitting. Our results show that the 2PT is an efficient method for studying the properties of water under various chemical and biological environments.« less

Authors:
 [1];  [2]; ; ;  [1]
  1. Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)
  2. (China)
Publication Date:
OSTI Identifier:
22419945
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DENSITY; ENTHALPY; ENTROPY; FREE ENERGY; MOLECULAR DYNAMICS METHOD; SOLIDS; TEMPERATURE DEPENDENCE; WATER

Citation Formats

Yeh, Kuan-Yu, Refining and Manufacturing Research Institute, CPC Corporation, Chia-Yi 60051, Taiwan, Huang, Shao-Nung, Chen, Li-Jen, E-mail: ljchen@ntu.edu.tw, E-mail: stlin@ntu.edu.tw, and Lin, Shiang-Tai, E-mail: ljchen@ntu.edu.tw, E-mail: stlin@ntu.edu.tw. Diffusive and quantum effects of water properties in different states of matter. United States: N. p., 2014. Web. doi:10.1063/1.4890572.
Yeh, Kuan-Yu, Refining and Manufacturing Research Institute, CPC Corporation, Chia-Yi 60051, Taiwan, Huang, Shao-Nung, Chen, Li-Jen, E-mail: ljchen@ntu.edu.tw, E-mail: stlin@ntu.edu.tw, & Lin, Shiang-Tai, E-mail: ljchen@ntu.edu.tw, E-mail: stlin@ntu.edu.tw. Diffusive and quantum effects of water properties in different states of matter. United States. doi:10.1063/1.4890572.
Yeh, Kuan-Yu, Refining and Manufacturing Research Institute, CPC Corporation, Chia-Yi 60051, Taiwan, Huang, Shao-Nung, Chen, Li-Jen, E-mail: ljchen@ntu.edu.tw, E-mail: stlin@ntu.edu.tw, and Lin, Shiang-Tai, E-mail: ljchen@ntu.edu.tw, E-mail: stlin@ntu.edu.tw. Mon . "Diffusive and quantum effects of water properties in different states of matter". United States. doi:10.1063/1.4890572.
@article{osti_22419945,
title = {Diffusive and quantum effects of water properties in different states of matter},
author = {Yeh, Kuan-Yu and Refining and Manufacturing Research Institute, CPC Corporation, Chia-Yi 60051, Taiwan and Huang, Shao-Nung and Chen, Li-Jen, E-mail: ljchen@ntu.edu.tw, E-mail: stlin@ntu.edu.tw and Lin, Shiang-Tai, E-mail: ljchen@ntu.edu.tw, E-mail: stlin@ntu.edu.tw},
abstractNote = {The enthalpy, entropy, and free energy of water are important physical quantities for understanding many interesting phenomena in biological systems. However, conventional approaches require different treatments to incorporate quantum and diffusive effects of water in different states of matter. In this work, we demonstrate the use of the two-phase thermodynamic (2PT) model as a unified approach to obtain the properties of water over the whole phase region of water from short (∼20 ps) classical molecular dynamics trajectories. The 2PT model provides an effective way to separate the diffusive modes (gas-like component) from the harmonic vibrational modes (solid-like component) in the vibrational density of states (DoS). Therefore, both diffusive and quantum effect can be properly accounted for water by applying suitable statistical mechanical weighting functions to the DoS components. We applied the 2PT model to systematically examine the enthalpy, entropy, and their temperature dependence of five commonly used rigid water models. The 2PT results are found to be consistent with those obtained from more sophisticated calculations. While the thermodynamic properties determined from different water models are largely similar, the phase boundary determined from the equality of free energy is very sensitive to the small inaccuracy in the values of enthalpy and absolute entropy. The enthalpy, entropy, and diffusivity of water are strongly interrelated, which challenge further improvement of rigid water model via parameter fitting. Our results show that the 2PT is an efficient method for studying the properties of water under various chemical and biological environments.},
doi = {10.1063/1.4890572},
journal = {Journal of Chemical Physics},
number = 4,
volume = 141,
place = {United States},
year = {Mon Jul 28 00:00:00 EDT 2014},
month = {Mon Jul 28 00:00:00 EDT 2014}
}
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