Calculation of diffusion coefficient for supercritical carbon dioxide and carbon dioxide+naphthalene system by molecular dynamics simulation using EPM2 model

金沢大大学理工研究域自然システム学系NVT ensemble molecular dynamics (MD) simulation has been applied to calculate the self-diffusion coefficients of carbon dioxide and the tracer diffusion coefficients of naphthalene in supercritical carbon dioxide. The simulation was carried out in the pressure range from 8 to 40MPa. The elementary physical model proposed by Harris and Yung was adopted for carbon dioxide and some approximation models were used for naphthalene. The systems of MD simulation for carbon dioxide consist of 256 particles. One naphthalene molecule was added for carbon dioxide+naphthalene system. The system can be assumed to be an infinite dilution condition for carbon dioxide+naphthalene system and the mutual diffusion coefficients are equal to the tracer diffusion coefficients of naphthalene. The self-diffusion coefficients of carbon dioxide and the tracer diffusion coefficients of naphthalene in supercritical carbon dioxide can be calculated by mean square displacement. The calculated results of diffusion coefficients showed good agreement with the experimental data without adjustable parameters. © 2010 Taylor & Francis

Estimation of boiling and melting points of light, heavy and complex hydrocarbons by means of a modified group vector space method

金沢大学大学院自然科学研究科生産プロセスA modified group vector space (GVS) method was developed for estimating the normal boiling points and melting points of alkanes, alkenes, alkynes, and cyclic and aromatic hydrocarbons including their isomers. The present method, based on group contributions as well as topological contributions, can represent the normal boiling points of isomeric compounds accurately. The group parameters for the modified GVS method were obtained from the correlation of the boiling and melting points of 1115 hydrocarbons. © 2005 Elsevier B.V. All rights reserved

Comparison of molecular models used in molecular dynamics simulation for tracer diffusion coefficients of naphthalene and dimethylnaphthalene isomers in supercritical carbon dioxide

金沢大学大学院自然科学研究科生産プロセスNVT ensemble molecular dynamics simulation was performed to calculate the tracer diffusion coefficients of naphthalene and dimethylnaphthalene isomers in supercritical carbon dioxide. Carbon dioxide was treated as a Lennard-Jones molecule (single site model) and solutes were treated as a rigid model of multi sites (united atom model) and a flexible model of all atoms (all atom model). The calculated results are compared with the experimental data and the calculated results by a single site model. The united atom model gives the best results to the experimental data among the three models. The calculated tracer diffusion coefficients by the all atom model show fairly good results without adjustable interaction parameters. © 2005 Elsevier B.V. All rights reserved

Solubilities and diffusion coefficients of high boiling compounds in supercritical carbon dioxide

金沢大学大学院自然科学研究科生産プロセスA brief introduction of the data sources and the applications of correlation methods for the solubilities and diffusion coefficients of hig-boiling compounds (mainly in solid state) in supercritical carbon dioxide are reviewed. Empirical equations, equations of state, solution models, and the Monte Carlo simulation for the calculation of solubilities in supercritical carbon dioxide are discussed. The application of empirical equation based on the Stokes-Einstein model, rough hard sphere theory, Schmidt number correlation, and molecular dynamics simulation for the calculation of diffusion coefficients in supercritical carbon dioxide at infinite dilution condition are reviewed. Further, the application of the Darken equation and the Leffler and Cullinan equation for the calculation of concentration dependence of diffusion coefficients in supercritical carbon dioxide is presented. © 2001 Elsevier Science Ltd. All rights reserved

Calculation of self-diffusion coefficients of the [BMIM][TFSA]/water system by molecular dynamics simulation

We performed a molecular dynamics simulation to calculate the self-diffusion coefficients of 1-Butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and water in a water–ionic liquid mixture. We then compared the simulated self-diffusion coefficients of cation, anion and water molecules with experimental data and with simulated data from the literature. Although the simulation overestimated the self-diffusion coefficients of ions, the simulated results qualitatively reproduced the enhancement of the self-diffusion coefficients of water as the water molar fraction increased. We also calculated the radial distribution functions to investigate the solution structure, i.e. the clustering of water molecules. The clustering of water in ionic liquid was found to play an important role in the enhancement of the diffusion of water molecules in the ionic liquid. © 2017 Informa UK Limited, trading as Taylor & Francis GroupEmbargo Period 12 month

Calculation of diffusion coefficients for carbon dioxide + solute system near the critical conditions by non-equilibrium molecular dynamics simulation

金沢大学大学院自然科学研究科生産プロセスA non-equilibrium molecular dynamics simulation was adopted to calculate the diffusion coefficients for a pseudo-binary system of carbon dioxide and for a carbon dioxide + solute system at 308.2 and 318.2K. The calculated results were compared with the self- and tracer diffusion coefficients calculated by an equilibrium molecular dynamics simulation. The simulated results for the pseudo-binary system of carbon dioxide by the non-equilibrium molecular dynamics simulation are in good agreement with the results of self diffusion coefficients for pure carbon dioxide by the equilibrium molecular dynamics simulation. The simulated results of mutual diffusion coefficients for the carbon dioxide + solute system by the non-equilibrium molecular dynamics simulation are slightly lower than the results of the tracer diffusion coefficients by the equilibrium molecular dynamics simulation. The anomalous behavior of diffusion coefficients near the critical concentration was represented by the results of the non-equilibrium molecular dynamics simulation. © 2004 Elsevier B.V. All rights reserved

Molecular dynamics simulation of diffusion coefficients of naphthalene and 2-naphthol in supercritical carbon dioxide

金沢大学大学院自然科学研究科生産プロセスNVT ensemble molecular dynamics simulation has been applied to calculate the diffusion coefficients of naphthalene and 2-naphthol in supercritical carbon dioxide in the pressure range from 8 to 40 MPa under infinite dilution conditions. The Lennard-Jones (12-6) potential function was used as the intermolecular potential. The calculation results showed good agreement with the experimental values, by using the intermolecular interaction parameters between unlike molecules which were determined by Monte Carlo simulation to give good representation for the solubilities of naphthalene and 2-naphthol in supercritical carbon dioxide