TY - COMP T1 - Gibbs 9.7.6 DA - 2024/// PY - 2024 PB - IFP Energies Nouvelles, Rueil-Malmaison & Université Paris Sud, CNRS CY - France ET - 9.7.6 TY - JOUR T1 - Optimization of the anisotropic united atoms intermolecular potential for n-alkanes AU - Ungerer,Philippe AU - Beauvais,Christèle AU - Delhommelle,Jérôme AU - Boutin,Anne AU - Rousseau,Bernard AU - Fuchs,Alain H. Y1 - 2000/03/09 PY - 2000 DA - 2000/03/22 N1 - doi: 10.1063/1.481116 DO - 10.1063/1.481116 T2 - The Journal of Chemical Physics JF - The Journal of Chemical Physics JO - J. Chem. Phys. SP - 5499 EP - 5510 VL - 112 IS - 12 PB - American Institute of Physics SN - 0021-9606 M3 - doi: 10.1063/1.481116 UR - https://doi.org/10.1063/1.481116 AB - The parameters of the anisotropic united atoms potential for linear alkanes proposed by Toxvaerd [S. Toxvaerd, J. Chem. Phys. 107, 5197 (1997)] have been optimized on the basis of selected equilibrium properties (vapor pressures, vaporization enthalpies, and liquid densities) of ethane, n-pentane, and n-dodecane. The optimized parameters for the CH2 and CH3 groups form a regular sequence with those of methane and the force centers are found between the carbon and hydrogen atoms, as expected. The resulting potential, called AUA4, has been compared with Toxvaerd’s potential (AUA3) by using several molecular simulation methods (Gibbs ensemble Monte Carlo, thermodynamic integration, and molecular dynamics). An investigation performed at temperatures ranging from 140 to 700 K and with various chain lengths up to 20 carbon atoms has shown AUA4 to provide systematic improvements of vapor pressures, vaporization enthalpies, and liquid densities for pure n-alkanes. Significant improvements have been also noticed on the critical temperatures of n-alkanes, estimated from coexistence density curves, and on the equilibrium properties of CO2–n-alkane binary mixtures. Self-diffusion coefficients of n-hexane, however, are slightly improved by the new potential, but still exceed experimental measurements at low temperature. As we have only optimized the intermolecular potential in the present study, it is suggested that further optimization of the intramolecular potentials of the anisotropic united atoms model could allow simultaneous prediction of thermodynamic properties and of transport coefficients, particularly in very dense liquids. ER - TY - JOUR T1 - New optimization method for intermolecular potentials: Optimization of a new anisotropic united atoms potential for olefins: Prediction of equilibrium properties AU - Bourasseau,Emeric AU - Haboudou,Mehalia AU - Boutin,Anne AU - Fuchs,Alain H. AU - Ungerer,Philippe Y1 - 2003/01/30 PY - 2003 DA - 2003/02/15 N1 - doi: 10.1063/1.1537245 DO - 10.1063/1.1537245 T2 - The Journal of Chemical Physics JF - The Journal of Chemical Physics JO - J. Chem. Phys. SP - 3020 EP - 3034 VL - 118 IS - 7 PB - American Institute of Physics SN - 0021-9606 M3 - doi: 10.1063/1.1537245 UR - https://doi.org/10.1063/1.1537245 ER - TY - JOUR T1 - Vapour-Liquid Phase Equilibria Predictions of Methane–Alkane Mixtures by Monte Carlo Simulation AU - Mackie, Allan D. AU - Tavitian, Bernard AU - Boutin, Anne AU - Fuchs, Alain H. Y1 - 1997/02/01 PY - 1997 DA - 1997/02/01 N1 - doi: 10.1080/08927029708024135 DO - 10.1080/08927029708024135 T2 - Molecular Simulation JF - Molecular Simulation JO - Molecular Simulation SP - 1 EP - 15 VL - 19 IS - 1 PB - Taylor & Francis AB - Abstract We report molecular simulations of methane?alkane mixtures using the Gibbs ensemble technique combined with the configurational-bias Monte Carlo method. The intermolecular interactions are modeled using both the united atom model with parameters proposed by Smit et al. and the anisotropic united atom model by Toxvaerd. Liquid-vapour phase diagrams are calculated for methane-n-pentane and methane-n-dodecane mixtures using these two potential models and compared with experimental results. SN - 0892-7022 M3 - doi: 10.1080/08927029708024135 UR - https://doi.org/10.1080/08927029708024135 ER - TY - JOUR T1 - Prediction of thermodynamic derivative properties of fluids by Monte Carlo simulation A1 - Lagache, M. A1 - Ungerer, P. A1 - Boutin, A. A1 - Fuchs, A. H. Y1 - 2001 SP - 4333 EP - 4339 JF - Physical Chemistry Chemical Physics JO - Phys. Chem. Chem. Phys. VL - 3 IS - 19 PB - The Royal Society of Chemistry SN - 1463-9076 DO - 10.1039/B104150A M3 - 10.1039/B104150A UR - http://dx.doi.org/10.1039/B104150A N2 - We compute second order derivatives of the Gibbs energy by Monte Carlo simulation in the isobaric–isothermal ensemble for fluids made of rigid and flexible molecules and test the accuracy of the simple interactions potential. The thermal expansivity and the isothermal compressibility can be calculated directly during a simulation run. The total heat capacity is obtained as the sum of the residual heat capacity computed using the fluctuation method and the ideal heat capacity, which cannot be determined by Monte Carlo simulation and must be taken from experimental data. The Joule–Thomson coefficient is obtained by the combined use of thermal expansivity and total heat capacity. The fluctuation method proves to converge very well, with limitation at low pressure for the Joule–Thomson coefficient. The fluctuation method has been extensively tested on pure light hydrocarbons (methane, ethane and butane) in the vapour and liquid states. In the case of methane, we used a united atom Lennard-Jones potential (D. Möller, J. Oprzynski, A. Müller and J. Fischer, . ., 1992, , 363). Detailed comparison with experimental heat capacities, volumetric properties and Joule–Thomson coefficients at pressures up to 100 MPa showed excellent agreement. The inversion of the Joule–Thomson effect is predicted with an excellent accuracy. In the case of ethane and n-butane, we used an anisotropic united atoms potential (P. Ungerer, C. Beauvais, J. Delhommelle, A. Boutin, B. Rousseau and A. H. Fuchs, . . ., 2000, , 5499). Comparison with experimental data available up to 10 MPa shows that ethane properties are well predicted. For n-butane, derivative properties have been determined in the gas and in the liquid state with good agreement in both phases. Finally, tests made on a methane–ethane system at pressures up to 100 MPa show that the fluctuation method can be extended to mixtures without any further complication. ER - TY - JOUR T1 - Monte Carlo simulation of branched alkanes and long chain n -alkanes with anisotropic united atoms intermolecular potential AU - Bourasseau, Emeric AU - Ungerer, Philippe AU - Boutin, Anne AU - Fuchs, Alain H. Y1 - 2002/04/01 PY - 2002 DA - 2002/04/01 N1 - doi: 10.1080/08927020290018723 DO - 10.1080/08927020290018723 T2 - Molecular Simulation JF - Molecular Simulation JO - Molecular Simulation SP - 317 EP - 336 VL - 28 IS - 4 PB - Taylor & Francis AB - The anisotropic united atoms potential for linear alkanes proposed by Ungerer (J. Chem. Phys. , 112 , 5499, 2000), called AUA4, has been used to predict several equilibrium properties (vapour pressure, vaporisation enthalpies, and liquid densities) of alkanes by Gibbs ensemble Monte Carlo simulation. In order to extend the potential to branched alkanes, potential parameters for the CH group have been determined by optimisation on the basis of equilibrium properties of isobutane, keeping the same parameters as AUA4 for the CH 3 groups. The resulting CH parameters form a regular sequence with those previously determined for CH3 and CH2 groups, so that a physically consistent parameter set is obtained. Simulations have been performed at temperatures ranging from 450 to 800 u K for long n -alkanes (C20, C25 and C30) and from 350 to 450 u K for four heptane isomers (n -heptane, 2-methylhexane, 2,4-dimethylpentane and 2-ethylpentane). In order to achieve internal relaxation of long chains with a good efficiency, a specific Monte Carlo move was used in which a united atom is rotated around its nearest neighbours. Equilibrium properties of long chain alkanes are well predicted, and small differences between heptane isomers are represented with a good accuracy. It is concluded that the AUA4 potential shows an interesting degree of transferability. SN - 0892-7022 M3 - doi: 10.1080/08927020290018723 UR - https://doi.org/10.1080/08927020290018723 ER - TY - JOUR T1 - Monte Carlo Simulations of Mixtures Involving Ketones and Aldehydes by a Direct Bubble Pressure Calculation AU - Ferrando, Nicolas AU - Lachet, Véronique AU - Boutin, Anne Y1 - 2010/07/08 PY - 2010 DA - 2010/07/08 N1 - doi: 10.1021/jp1031724 DO - 10.1021/jp1031724 T2 - The Journal of Physical Chemistry B JF - The Journal of Physical Chemistry B JO - J. Phys. Chem. B SP - 8680 EP - 8688 VL - 114 IS - 26 PB - American Chemical Society N2 - Ketone and aldehyde molecules are involved in a large variety of industrial applications. Because they are mainly present mixed with other compounds, the prediction of phase equilibrium of mixtures involving these classes of molecules is of first interest particularly to design and optimize separation processes. The main goal of this work is to propose a transferable force field for ketones and aldehydes that allows accurate molecular simulations of not only pure compounds but also complex mixtures. The proposed force field is based on the anisotropic united-atoms AUA4 potential developed for hydrocarbons, and it introduces only one new atom, the carbonyl oxygen. The Lennard-Jones parameters of this oxygen atom have been adjusted on saturated thermodynamic properties of both acetone and acetaldehyde. To simulate mixtures, Monte Carlo simulations are carried out in a specific pseudoensemble which allows a direct calculation of the bubble pressure. For polar mixtures involved in this study, we show that this approach is an interesting alternative to classical calculations in the isothermal−isobaric Gibbs ensemble. The pressure−composition diagrams of polar + polar and polar + nonpolar binary mixtures are well reproduced. Mutual solubilities as well as azeotrope location, if present, are accurately predicted without any empirical binary interaction parameters or readjustment. Such result highlights the transferability of the proposed force field, which is an essential feature toward the simulation of complex oxygenated mixtures of industrial interest. AB - Ketone and aldehyde molecules are involved in a large variety of industrial applications. Because they are mainly present mixed with other compounds, the prediction of phase equilibrium of mixtures involving these classes of molecules is of first interest particularly to design and optimize separation processes. The main goal of this work is to propose a transferable force field for ketones and aldehydes that allows accurate molecular simulations of not only pure compounds but also complex mixtures. The proposed force field is based on the anisotropic united-atoms AUA4 potential developed for hydrocarbons, and it introduces only one new atom, the carbonyl oxygen. The Lennard-Jones parameters of this oxygen atom have been adjusted on saturated thermodynamic properties of both acetone and acetaldehyde. To simulate mixtures, Monte Carlo simulations are carried out in a specific pseudoensemble which allows a direct calculation of the bubble pressure. For polar mixtures involved in this study, we show that this approach is an interesting alternative to classical calculations in the isothermal−isobaric Gibbs ensemble. The pressure−composition diagrams of polar + polar and polar + nonpolar binary mixtures are well reproduced. Mutual solubilities as well as azeotrope location, if present, are accurately predicted without any empirical binary interaction parameters or readjustment. Such result highlights the transferability of the proposed force field, which is an essential feature toward the simulation of complex oxygenated mixtures of industrial interest. SN - 1520-6106 M3 - doi: 10.1021/jp1031724 UR - https://doi.org/10.1021/jp1031724 ER -