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Ramos JE. Effective intermolecular potential and critical point for C 60 molecule. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2017.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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2
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Abramo MC, Caccamo C, Costa D, Munaò G. Communication: Phase diagram of C₃₆ by atomistic molecular dynamics and thermodynamic integration through coexistence regions. J Chem Phys 2014; 141:091103. [PMID: 25194357 DOI: 10.1063/1.4894809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report an atomistic molecular dynamics determination of the phase diagram of a rigid-cage model of C36. We first show that free energies obtained via thermodynamic integrations along isotherms displaying "van der Waals loops," are fully reproduced by those obtained via isothermal-isochoric integration encompassing only stable states. We find that a similar result also holds for isochoric paths crossing van der Waals regions of the isotherms, and for integrations extending to rather high densities where liquid-solid coexistence can be expected to occur. On such a basis we are able to map the whole phase diagram of C36, with resulting triple point and critical temperatures about 1770 K and 2370 K, respectively. We thus predict a 600 K window of existence of a stable liquid phase. Also, at the triple point density, we find that the structural functions and the diffusion coefficient maintain a liquid-like character down to 1400-1300 K, this indicating a wide region of possible supercooling. We discuss why all these features might render possible the observation of the melting of C36 fullerite and of its liquid state, at variance with what previously experienced for C60.
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Affiliation(s)
- M C Abramo
- Dipartimento di Fisica e di Scienze della Terra, Università degli Studi di Messina and CNISM (Consorzio Nazionale Interuniversitario di Struttura della Materia) Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - C Caccamo
- Dipartimento di Fisica e di Scienze della Terra, Università degli Studi di Messina and CNISM (Consorzio Nazionale Interuniversitario di Struttura della Materia) Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - D Costa
- Dipartimento di Fisica e di Scienze della Terra, Università degli Studi di Messina and CNISM (Consorzio Nazionale Interuniversitario di Struttura della Materia) Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - G Munaò
- Dipartimento di Fisica e di Scienze della Terra, Università degli Studi di Messina and CNISM (Consorzio Nazionale Interuniversitario di Struttura della Materia) Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
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3
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Affiliation(s)
- C. Patrick Royall
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - Stephen R. Williams
- Research School of Chemistry, Australian National University, Canberra, ACT 0200 Australia
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Ngale KN, Desgranges C, Delhommelle J. Nucleation and growth of C60 nanoparticles from the supersaturated vapor and from the undercooled liquid: A molecular simulation study. J Chem Phys 2009; 131:244515. [DOI: 10.1063/1.3283901] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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5
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Zhou S. Reformulation of liquid perturbation theory for low temperatures. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:011126. [PMID: 19257020 DOI: 10.1103/physreve.79.011126] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 10/03/2008] [Indexed: 05/27/2023]
Abstract
A perturbation strategy is proposed which allows liquid perturbation methodology to be applied to extremely low temperature situations for which the available liquid integral equation theory and traditional thermodynamic perturbation theory fail. The possibility of avoiding the low temperature problem of the thermodynamic perturbation theory not only is of relevance to the investigation of complex fluids, but also may be useful for reformulation of other liquid theories to achieve higher accuracy and avoid the respective low temperature problems.
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Affiliation(s)
- Shiqi Zhou
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan, China, 410083.
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6
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Abramo MC, Caccamo C. Atomistic molecular dynamics simulations of model C36 fullerite. J Chem Phys 2008; 128:074503. [DOI: 10.1063/1.2837294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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7
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Costa D, Ruberto R, Sciortino F, Abramo MC, Caccamo C. Glass transition line in C60: a mode-coupling/molecular-dynamics study. J Phys Chem B 2007; 111:10759-64. [PMID: 17705420 DOI: 10.1021/jp072186v] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report a study of the mode-coupling theory (MCT) glass transition line for the Girifalco model of C60 fullerene. The equilibrium static structure factor of the model, the only required input for the MCT calculations, is provided by molecular dynamics simulations. The glass transition line develops inside the metastable liquid-solid coexistence region and extends down in temperature, terminating on the liquid side of the metastable portion of the liquid-vapor binodal. The vitrification locus does not show re-entrant behavior. A comparison with previous computer simulation estimates of the location of the glass line suggests that the theory accurately reproduces the shape of the arrest line in the density-temperature plane. The theoretical HNC and MHNC structure factors (and consequently the corresponding MCT glass line) compare well with the numerical counterpart. Our results confirm the conclusion drawn in previous works about the existence of a glassy phase for the fullerene model at issue.
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Affiliation(s)
- D Costa
- Dipartimento di Fisica, Università di Messina and CNISM Ctr Papardo, 98166 Messina, Italy.
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8
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Malescio G. Complex phase behaviour from simple potentials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:073101. [PMID: 22251582 DOI: 10.1088/0953-8984/19/7/073101] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Simple pair potentials, where the term 'simple' denotes potentials that are isotropic and refer to one-component systems, can be used to describe effective interactions among substances with supramolecular architecture. By suitably choosing the functional dependence on the intermolecular distance, through such potentials it is possible to take into account, in an average way, the effect of the internal degrees of freedom of the macromolecules. This may give rise to phase phenomena that are radically different from those characterizing typical monoatomic systems. Here we review a number of simple model potentials presenting unusual, i.e. not argon-like, features and discuss the role of attraction and repulsion in determining their phase behaviour.
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Affiliation(s)
- G Malescio
- Dipartimento di Fisica, Università di Messina, 98166 Messina, Italy
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Chang J, Sandler SI. Free energy of the solid C60 fullerene orientational order-disorder transition. J Chem Phys 2006; 125:054705. [PMID: 16942239 DOI: 10.1063/1.2219753] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The free energies of the orientationally ordered crystal phase of C60 at low temperatures and the disordered crystal phase at high temperatures are calculated to an accuracy of +/-0.05 kJ/mol using the expanded ensemble Monte Carlo method with the potential model of Sprik et al. [J. Phys. Chem. 96, 2027 (1992)]. The order-disorder transition temperature at zero pressure is determined directly from these free energies, and is found to be consistent with the abrupt changes in configurational energy and unit cell size also found in simulation. A modification of the potential results in predictions of the transition temperature of 257 K and the entropy change of 18.1 J/mol K at this transition, which are in good agreement with the experimental values of 260 K and 19 J/mol K, respectively. The orientational distinguishability in the ordered phase and the indistinguishability in the disordered phase lead to a contribution to the entropy difference of k ln 60, with 60 being the symmetry number of C60. This quantum mechanical correction is important for the accurate prediction of the phase transition properties of the C60 crystals.
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Affiliation(s)
- Jaeeon Chang
- Center for Molecular and Engineering Thermodynamics, Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, USA
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Apte PA, Kusaka I. Direct calculation of solid-vapor coexistence points by thermodynamic integration: application to single component and binary systems. J Chem Phys 2006; 124:184106. [PMID: 16709096 DOI: 10.1063/1.2193148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a new thermodynamic integration method that directly connects the vapor and solid phases by a reversible path. The thermodynamic integration in the isothermal-isobaric ensemble yields the Gibbs free energy difference between the two phases, from which the sublimation temperature can be easily calculated. The method extends to the binary mixture without any modification to the integration path simply by employing the isothermal-isobaric semigrand ensemble. The thermodynamic integration, in this case, yields the chemical potential difference between the solid and vapor phases for one of the components, from which the binary sublimation temperature can be calculated. The coexistence temperatures predicted by our method agree well with those in the literature for single component and binary Lennard-Jones systems.
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Affiliation(s)
- Pankaj A Apte
- The Koffolt Laboratories, The Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, USA
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Paricaud P. A general perturbation approach for equation of state development: Applications to simple fluids, ab initio potentials, and fullerenes. J Chem Phys 2006; 124:154505. [PMID: 16674240 DOI: 10.1063/1.2181979] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A new perturbation scheme based on the Barker-Henderson perturbation theory [J. Chem. Phys. 47, 4714 (1967)] is proposed to predict the thermodynamic properties of spherical molecules. Accurate predictions of second virial coefficients and vapor-liquid coexistence properties are obtained for a large variety of potential functions (square well, Yukawa, Sutherland, Lennard-Jones, Buckingham, Girifalco). New Gibbs ensemble Monte Carlo simulations of the generalized exp-m Buckingham potential are reported. An extension of the perturbation approach to mixtures is proposed, and excellent predictions of vapor-liquid equilibria are obtained for Lennard-Jones mixtures. The perturbation scheme can be applied to complex potential functions fitted to ab initio data to predict the properties of real molecules such as neon. The new approach can also be used as an auxiliary tool in molecular simulation studies, to efficiently optimize an intermolecular potential on macroscopic properties or match force fields based on different potential functions.
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Affiliation(s)
- Patrice Paricaud
- Laboratoire Chimie et Procédé, UCP-ENSTA, 32 Boulevard Victor, 75739 Paris, France.
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12
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Abramo MC, Caccamo C, Costa D, Ruberto R. Phase and Glass Transitions in Short-Range Central Potential Model Systems: The Case of C60. J Phys Chem B 2005; 109:24077-84. [PMID: 16375400 DOI: 10.1021/jp054392d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Extensive molecular dynamics simulations show that a short-range central potential, suited to model C60, undergoes a high temperature transition to a glassy phase characterized by the positional disorder of the constituent particles. Crystallization, melting, and sublimation, which also take place during the simulation runs, are illustrated in detail. It turns out that vitrification and the mentioned phase transitions occur when the packing fraction of the system-defined in terms of an effective hard-core diameter-equals that of hard spheres at their own glass and melting transition, respectively. A close analogy also emerges between our findings and recent mode coupling theory calculations of structural arrest lines in a similar model of protein solutions. We argue that the conclusions of the present study might hold for a wide class of potentials currently employed to mimic interactions in complex fluids (some of which are of biological interest), suggesting how to achieve at least qualitative predictions of vitrification and crystallization in those systems.
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Affiliation(s)
- Maria C Abramo
- Dipartimento di Fisica, Università degli Studi di Messina, Contrada Papardo, C.P. 50-98166 Messina, Italy
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Li L, Bedrov D, Smith GD. A molecular-dynamics simulation study of solvent-induced repulsion between C60 fullerenes in water. J Chem Phys 2005; 123:204504. [PMID: 16351278 DOI: 10.1063/1.2121647] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular-dynamics simulations of a single C(60) fullerene and pairs of C(60) fullerenes in aqueous solution have been performed for the purpose of obtaining improved understanding of the nature of solvent-induced interactions between C(60) fullerenes in water. Our simulations reveal repulsive solvent-induced interactions between two C(60) fullerenes in aqueous solution in contrast to the associative effects observed for conventional nonpolar solutes. A decomposition of the solvent-induced potential of mean force between fullerenes into entropy and energy (enthalpy) contributions reveals that the water-induced repulsion between fullerenes is energetic in origin, contrasting strongly to entropy-driven association observed for conventional nonpolar solutes. The dominance of energy in the solvent-induced interactions between C(60) fullerenes arises primarily from the high atomic density of the C(60) molecule, resulting in strong C(60)-water van der Waals attraction that is reduced upon association of the fullerenes. The water-induced repulsion is found to decrease with increasing temperature due largely to an increasing contribution from a relatively weak entropy-driven association.
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Affiliation(s)
- Liwei Li
- Department of Materials Science and Engineering and Department of Chemical Engineering, University of Utah, Salt Lake City, UT 84112, USA
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14
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Abramo MC, Caccamo C, Costa D, Ruberto R. High-Temperature Glass Transition in Model C60. J Phys Chem B 2004. [DOI: 10.1021/jp046995f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maria C. Abramo
- Istituto Nazionale per la Fisica della Materia (INFM) andDipartimento di Fisica, Università degli Studi di Messina, Contrada Papardo, C.P. 50-98166 Messina, Italy
| | - Carlo Caccamo
- Istituto Nazionale per la Fisica della Materia (INFM) andDipartimento di Fisica, Università degli Studi di Messina, Contrada Papardo, C.P. 50-98166 Messina, Italy
| | - Dino Costa
- Istituto Nazionale per la Fisica della Materia (INFM) andDipartimento di Fisica, Università degli Studi di Messina, Contrada Papardo, C.P. 50-98166 Messina, Italy
| | - Romina Ruberto
- Istituto Nazionale per la Fisica della Materia (INFM) andDipartimento di Fisica, Università degli Studi di Messina, Contrada Papardo, C.P. 50-98166 Messina, Italy
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15
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Silva Fernandes FMS, Freitas FFM, Fartaria RPS. Phase Diagram and Sublimation Enthalpies of Model C60 Revisited. J Phys Chem B 2004. [DOI: 10.1021/jp049399u] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Fernando M. S. Silva Fernandes
- Laboratory of Molecular Simulation and CECUL, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa, Rua Ernesto de Vasconcelos, Bloco C8, Piso 3, 1749-016 Lisboa, Portugal
| | - Filomena F. M. Freitas
- Laboratory of Molecular Simulation and CECUL, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa, Rua Ernesto de Vasconcelos, Bloco C8, Piso 3, 1749-016 Lisboa, Portugal
| | - Rui P. S. Fartaria
- Laboratory of Molecular Simulation and CECUL, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa, Rua Ernesto de Vasconcelos, Bloco C8, Piso 3, 1749-016 Lisboa, Portugal
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16
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Ben-Amotz D, Stell G. Reformulation of Weeks−Chandler−Andersen Perturbation Theory Directly in Terms of a Hard-Sphere Reference System. J Phys Chem B 2004. [DOI: 10.1021/jp037810s] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dor Ben-Amotz
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907
| | - George Stell
- State University of New York, Stony Brook, New York 11794
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17
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Abramo MC, Caccamo C, Costa D, Pellicane G, Ruberto R. Atomistic versus two-body central potential models of C(60): a comparative molecular dynamics study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 69:031112. [PMID: 15089270 DOI: 10.1103/physreve.69.031112] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Indexed: 05/24/2023]
Abstract
We report on an extensive molecular dynamics investigation of two models of C60. The first model is based on an effective pair, central potential obtained by integrating the interaction between two carbon atoms over the fullerene cages [L.A. Girifalco, J. Phys. Chem. 96, 858 (1992)]. The second model explicitly takes into account the discrete, "atomistic" structure of the C60 molecules; we study two different parametrizations of the carbon-carbon interaction, one identical to that employed in the Girifalco approach, the other borrowed from previous studies on graphite [A. Cheng and M.L. Klein, J. Phys. Chem. 95, 6750 (1991)]. We consider a temperature range spanning from 300 to 1900 K, and pressures up to 200 kbar. Results for the lattice spacing and several thermodynamic quantities, as well as for the radial distribution functions, are reported and compared among each other and with experimental data. The central pair model yields only semiquantitative predictions at typical ambient densities, whereas pressures are generally overestimated. Atomistic simulations reproduce to an overall quantitative level of accuracy the experimental C60 properties. A comparison is also made of the central versus the atomistic potential predictions, when using the same potential parameters in the carbon-carbon interaction. We discuss applications of the adopted modelizations to fullerene systems of current interest, as well as different strategies to optimize the values of the potential parameters.
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Affiliation(s)
- M C Abramo
- Istituto Nazionale per la Fisica della Materia (INFM) and Dipartimento di Fisica, Università di Messina, Contrada Papardo, C.P. 50, 98166 Messina, Italy.
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18
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Ben-Amotz D, Stell G. Analytical implementation and critical tests of fluid thermodynamic perturbation theory. J Chem Phys 2003. [DOI: 10.1063/1.1620995] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Chen B, Siepmann JI, Karaborni S, Klein ML. Vapor−Liquid and Vapor−Solid Phase Equilibria of Fullerenes: The Role of the Potential Shape on the Triple Point. J Phys Chem B 2003. [DOI: 10.1021/jp0361069] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bin Chen
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455-0431, Pharmaceutical Research & Development, Merck & Company Inc., P.O. Box 4, WP78-304, West Point, Pennsylvania 19486, and Center for Molecular Modeling and Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia,
| | - J. Ilja Siepmann
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455-0431, Pharmaceutical Research & Development, Merck & Company Inc., P.O. Box 4, WP78-304, West Point, Pennsylvania 19486, and Center for Molecular Modeling and Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia,
| | - Sami Karaborni
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455-0431, Pharmaceutical Research & Development, Merck & Company Inc., P.O. Box 4, WP78-304, West Point, Pennsylvania 19486, and Center for Molecular Modeling and Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia,
| | - Michael L. Klein
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803-1804, Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455-0431, Pharmaceutical Research & Development, Merck & Company Inc., P.O. Box 4, WP78-304, West Point, Pennsylvania 19486, and Center for Molecular Modeling and Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia,
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Costa D, Pellicane G, Caccamo C, Schöll-Paschinger E, Kahl G. Theoretical description of phase coexistence in model C60. ACTA ACUST UNITED AC 2003; 68:021104. [PMID: 14524950 DOI: 10.1103/physreve.68.021104] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2003] [Indexed: 11/07/2022]
Abstract
We have investigated the phase diagram of a pair interaction model of C60 fullerene [L. A. Girifalco, J. Phys. Chem. 96, 858 (1992)], in the framework provided by two integral equation theories of the liquid state, namely, the modified hypernetted chain (MHNC) implemented under a global thermodynamic consistency constraint, and the self-consistent Ornstein-Zernike approximation (SCOZA), and by a perturbation theory (PT) with various degrees of refinement, for the free energy of the solid phase. We present an extended assessment of such theories as set against a recent Monte Carlo study of the same model [D. Costa, G. Pellicane, C. Caccamo, and M. C. Abramo, J. Chem. Phys. 118, 304 (2003)]. We have compared the theoretical predictions with the corresponding simulation results for several thermodynamic properties such as the free energy, the pressure, and the internal energy. Then we have determined the phase diagram of the model, by using either the SCOZA, the MHNC, or the PT predictions for one of the coexisting phases, and the simulation data for the other phase, in order to separately ascertain the accuracy of each theory. It turns out that the overall appearance of the phase portrait is reproduced fairly well by all theories, with remarkable accuracy as for the melting line and the solid-vapor equilibrium. All theories show a more or less pronounced discrepancy with the simulated fluid-solid coexistence pressure, above the triple point. The MHNC and SCOZA results for the liquid-vapor coexistence, as well as for the corresponding critical points, are quite accurate; the SCOZA tends to underestimate the density corresponding to the freezing line. All results are discussed in terms of the basic assumptions underlying each theory. We have then selected the MHNC for the fluid and the first-order PT for the solid phase, as the most accurate tools to investigate the phase behavior of the model in terms of purely theoretical approaches. It emerges that the use of different procedures to characterize the fluid and the solid phases provides a semiquantitative reproduction of the thermodynamic properties of the C60 model at issue. The overall results appear as a robust benchmark for further theoretical investigations on higher order C(n>60) fullerenes, as well as on other fullerene-related materials, whose description can be based on a modelization similar to that adopted in this work.
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Affiliation(s)
- D Costa
- Istituto Nazionale per la Fisica della Materia (INFM) and Dipartimento di Fisica, Università di Messina, Contrada Papardo, Cassella Postale 50, 98166 Messina, Italy.
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