Kinetic Monte Carlo approach for molecular modeling of adsorption

Ustinov, E. A.

doi:10.1016/j.coche.2018.12.004

Cited by 22 publications

(18 citation statements)

References 48 publications

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“…Here, μ°(T) is the standard chemical potential, and A is the surface area. Combining eqs 12 and 13, we get the required expression for the excess chemical potential: 72,73,81,82…”

Section: External Potentialmentioning

confidence: 99%

“…The external potential can be positive or negative and its variation affects the chemical potential of the whole system and allows for evaluating fundamental dependences such as the dependence of the pressure on the chemical potential. This technique based on the kinetic Monte Carlo simulation in an elongated cell was successfully used in a large number of applications. − The only shortcoming is that in the case of large molecules interacting with each other with a substantially high potential energy, the density of the equilibrium gas phase is too small to determine the chemical potential reliably. The combination of the two external fields resolves this problem because the damping field transforms the gas phase to the ideal gas of any density, while the external potential allows for keeping the crystal at any pressure.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…, According to the concept put forward in ref , the chemical potential and the molecular flux in the case of the 2D system are linked by the expression: Here, μ°( T ) is the standard chemical potential, and A is the surface area. Combining eqs and , we get the required expression for the excess chemical potential: ,,, Here, angle brackets denote the ensemble average, not the time average. The summation is performed over the whole system.…”

Section: Theoretical Modelmentioning

confidence: 99%

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Thermodynamics of Rigid Self-Assembled Crystals: Molecular Simulation of Two-Phase Systems under External Fields

2021

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A general methodology for determining the thermodynamic characteristics of orientationally ordered rigid crystals is presented. The basic problem here is associated with a very small flux of primary molecules that are released from a narrow interface and carry main information on thermodynamic properties of the crystal. The proposed approach is based on the kinetic Monte Carlo simulation of the gas−crystal system with an external "damping field" that reduces the intermolecular potential at the crystal edges and switches it off in the gas phase. Such a technique increases the primary molecular flux by several orders of magnitude, which is crucial for accurate determination of thermodynamic functions. In this study, we applied the approach to the thermodynamic analysis of the trimesic acid monolayer, explicitly accounting for hydrogen bonds, the dispersion, and electrostatic potentials. We considered equations of state, heat capacities, Helmholtz free energies, and entropies of three polymorphous structures: honeycomb, flower-like, and hexagonally close-packed structures in a wide range of temperatures and pressures. The calculated free energy and entropy excellently obey the Gibbs−Duhem equation, which confirms the thermodynamic consistency of our approach. The role of hydrogen bonds in the stability of different phases, as well as the condition of phase transitions, was also considered.

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“…Here, μ°(T) is the standard chemical potential, and A is the surface area. Combining eqs 12 and 13, we get the required expression for the excess chemical potential: 72,73,81,82…”

Section: External Potentialmentioning

confidence: 99%

Section: Theoretical Modelmentioning

confidence: 99%

Section: Theoretical Modelmentioning

confidence: 99%

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Thermodynamics of Rigid Self-Assembled Crystals: Molecular Simulation of Two-Phase Systems under External Fields

2021

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“…Since the chemical potential is the same in any point of the equilibrium system, the determined chemical potential for the gas phase is equal to that of the dense phase. The efficiency of this group of methods was enhanced by using the kinetic Monte Carlo (kMC) scheme. , The reason is that, in each kMC step, the molecule to be displaced is selected not randomly as in the standard MC algorithm but proportionally to the exponential function of its potential energy (or rate), which is much larger for the gas phase compared to that of the crystal (sometimes in several orders of magnitude). This makes the gas phase significantly more statistically representative and substantially reduces statistical errors in the chemical potential, which is especially important when the gas phase is extremely rarefied.…”

Section: Introductionmentioning

confidence: 99%

Chemical Potential and Thermodynamic Properties of Self-Assembled Monolayers: A Method of External Fields in a Monte Carlo Simulation

2020

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This study presents a method of external fields to determine thermodynamic characteristics of rigid crystalline phases in the framework of a kinetic Monte Carlo algorithm. The method is based on modeling of the gas−crystal system with explicit accounting for the interface and uses the condition of equal chemical potentials in coexisting phases. Two non-uniform fields are imposed on the gas phase. The first one is the usual external potential, while the other is a proposed-here damping field reducing intermolecular potentials up to zero. This makes the coexisting gas always ideal at any desired density under controlled crystal pressure. It opens an efficient way to reliably determine the chemical potential of very rigid solids. The effect of changing the damping field along the simulation cell is similar to that produced by the temperature gradient, but the condition of equilibrium is not violated. The approach was tested on the model of a self-assembled layer of trimesic acid at specified values of temperature and pressure. In all cases, thermodynamic consistency of the approach was convincingly confirmed. The proposed approach is a promising tool for modeling rigid crystalline structures such as self-assembled monolayers formed by relatively large functional organic molecules.

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“…The kMC was extended to understand equilibrium systems with the canonical ensemble for the simulation of vapor–liquid equilibrium, as well as adsorption on surfaces and in confined spaces. , However, the canonical ensemble is limited to a closed system, and thus further extensions involve the grand canonical ensemble for the simulation of an open system, isothermal–isobaric ensemble to determine the state of the system, and Gibbs- NVT ensembles to determine the saturated properties of the mixture . One key advantage of kMC compared to the conventional Metropolis Monte Carlo is the direct, highly accurate determination of the chemical potentials in both dilute and dense phases. , The equilibrium studies via kMC are summarized in an earlier work …”

Section: Introductionmentioning

confidence: 99%

Competitive and Synergistic Adsorption of Mixtures of Polar and Nonpolar Gases in Carbonaceous Nanopores

2021

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Most adsorption applications involve mixtures, yet accurate predictions of the adsorption of mixtures remain challenging, in part due to the inability to account for the interplay between adsorbate−adsorbate and adsorbate−adsorbent interactions. This study involves a comprehensive Monte Carlo simulation of the adsorption of two groups of mixtures (namely, supercritical and subcritical ones) in carbon nanopores and quantifies Henry's constants, isotherms, energetics, and density distributions in the pores. When interadsorbate interactions are negligible (e.g., in supercritical mixtures such as mixtures of nonpolar gases), adsorbates behave like ideal gases and the adsorption isotherm can be predicted with the ideal adsorbed solution theory (IAST). However, when interadsorbate interactions become significant, IAST fails. This study reveals that (1) in mixtures of polar and nonpolar gases, the stronger intermolecular interaction for the polar constituent leads to synergistic adsorption that causes the nonpolar adsorbate to desorb and (2) for mixtures of polar gases, such as ethanol and water, the adsorbate−adsorbate interactions are so dominant that the unfavorable adsorbate−adsorbent interactions are overcome, such that water adsorbs onto the hydrophobic adsorbent. The competitive and synergistic interactions highlighted here are expected to be valuable in enhancing gas separations.

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Kinetic Monte Carlo approach for molecular modeling of adsorption

Cited by 22 publications

References 48 publications

Thermodynamics of Rigid Self-Assembled Crystals: Molecular Simulation of Two-Phase Systems under External Fields

Thermodynamics of Rigid Self-Assembled Crystals: Molecular Simulation of Two-Phase Systems under External Fields

Chemical Potential and Thermodynamic Properties of Self-Assembled Monolayers: A Method of External Fields in a Monte Carlo Simulation

Competitive and Synergistic Adsorption of Mixtures of Polar and Nonpolar Gases in Carbonaceous Nanopores

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