An Efficient Algorithm for Molecular Density Functional Theory in Cylindrical Geometry: Application to Interfacial Statistical Associating Fluid Theory (iSAFT)

Xi, Shun; Liu, Jinlu; Parambathu, Arjun Valiya; Zhang, Yuchong; Chapman, Walter G.

doi:10.1021/acs.iecr.9b06895

Cited by 14 publications

(24 citation statements)

References 67 publications

(137 reference statements)

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“…In this context, classical density-functional theory (DFT) − has been instrumental in complementing both molecular-simulation and experimental studies and in providing valuable insights concerning the behavior of inhomogeneous fluids. On the other hand, the statistical associating fluid theory (SAFT) , has been a very successful tool for predicting the thermodynamic properties of homogeneous fluids. , There is a growing interest in SAFT-DFT − as well as 2D-SAFT − approaches to study inhomogeneous fluids. In these approaches, traditionally, fluid–solid interactions are accounted for using simplified coarse-grained (CG) representations; the (atomistic) details of the solid are not incorporated explicitly but, instead, are accounted for in an effective manner.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo Molecular Simulation Study of Carbon Dioxide Sequestration into Dry and Wet Calcite Pores Containing Methane

et al. 2021

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We perform grand canonical Monte Carlo (GCMC) simulations to study the adsorption of carbon dioxide in a calcite slit pore. The injection of carbon dioxide is simulated by increasing the chemical potential of carbon dioxide, which allows for an investigation of adsorption under varying carbon dioxide loadings. The study is carried out for three different environments: an empty pore; a pore containing methane; and a pore containing methane with trace amounts of water. We systematically investigate the impact of the presence of these other fluids on carbon dioxide adsorption. We study the influence of carbon dioxide loading on fluid density in the pore and examine individual fluid-density profiles (in the direction normal to the fluid−solid interface). The order of fluid adsorption affinity to the surface is found to be water > carbon dioxide > methane. The interpretation of our results is informed by the examination of free-energy-averaged fluid−substrate potentials, which are computed independently from the simulations. Our observations suggest that ignoring the presence of water could lead to overestimation not only of methane availability but also of carbon dioxide storage capacity in pores, with important consequences in, for example, modeling carbon dioxide sequestration in calcite-rich reservoirs. Ultimately, it is hoped that the molecular-level insights from this study will aid the multiscale modeling of reservoir fluids in the context of enhanced oil recovery and carbon dioxide sequestration.

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Section: Introductionmentioning

confidence: 99%

Monte Carlo Molecular Simulation Study of Carbon Dioxide Sequestration into Dry and Wet Calcite Pores Containing Methane

et al. 2021

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“…Also, the behavior of complex fluid with different types of interactions are interesting in some cases. For this purpose, the Statistical Associating Fluid Theory (SAFT) [22,31,32] is actively developed; due to the consideration of chain types of bonds in the molecule, association, dispersion contribution, an additional term appears in the free energy expression. All the of types the interaction might be expressed in a different way in Helmholtz free energy, for which it is also necessary to calculate the variation.…”

Section: Variation Free Methodsmentioning

confidence: 99%

“…The most significant change undergone the part with the variation of attraction interaction. Depending on what material is being investigated, the variation of free energy has to be calculated in different coordinate systems [21,22], which means variations should be recalculated in appropriate coordinates. Moreover, for describing polymers or other complex fluids Statistical Associating Fluid Theory (SAFT) is usually used, which considers dispersion, association, and chain contributions in Helmholtz energy [22].…”

mentioning

confidence: 99%

“…Depending on what material is being investigated, the variation of free energy has to be calculated in different coordinate systems [21,22], which means variations should be recalculated in appropriate coordinates. Moreover, for describing polymers or other complex fluids Statistical Associating Fluid Theory (SAFT) is usually used, which considers dispersion, association, and chain contributions in Helmholtz energy [22]. SAFT is an advanced technique for describing real fluids, but it has many modifications for which variations should be calculated.…”

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confidence: 99%

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Variation Free Approach for Molecular Density Functional Theory: Data-driven Stochastic Optimization

Kanygin,

Nesterova,

Lomovitskiy

et al. 2020

Preprint

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Density functional theory (DFT) is an efficient instrument for describing a wide range of nanoscale phenomena: wetting transition, capillary condensation, adsorption, etc. In this paper, we suggest a method for obtaining the equilibrium molecular fluid density in a nanopore using DFT without calculating the free energy variation Variation Free Density Functional Theory (VF-DFT). This technique can be used to explore confined fluids with a complex type of interactions, additional constraints and to speed up calculations. The fluid density in VF-DFT approach is represented as a decomposition over a limited set of basis functions. We applied principal component analysis (PCA) to extract the main patterns of the confined fluid density and build desired basis functions. The decomposition coefficients of the fluid density by the basis were sought by stochastic optimization algorithms: genetic algorithm (GA), particle swarm optimization (PSO) to minimize the free energy of the system. In this work, two different fluids were studied: nitrogen at a temperature of 77.4 K and argon 87.3 K, at a pore of 3.6 nm, and the performance of optimization algorithms was compared. We also introduce the Hybrid Density Functional Theory (H-DFT) approach based on stochastic optimization methods and the classical Picard iteration method to find the equilibrium fluid density starting from the physically appropriate solution. The combination of these methods helps to significantly speed up the calculations of equilibrium density in the system without losing the quality of the solution, especially in cases with the high pressure and expressed layering structure.

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“…Several approaches have been proposed to speed up the DFT calculations, for example, Fourier transform, fast Hankel transform, − massively parallel GPU-accelerated minimization, Anderson mixing, multiscale finite element, and so forth. Especially, an algorithm, that is, Chebyshev pseudo-spectral collocation method, has been proposed by Yatsyshin et al , and further developed by Nold et al This algorithm can provide an efficient and accurate calculation for wetting, condensation, and other inhomogeneous properties. − However, this algorithm has only been applied to model the Lennard-Jones fluids, and its performance on the complex fluids still requires further investigation.…”

Section: Introductionmentioning

confidence: 99%

Accelerate the ePC-SAFT-DFT Calculation with the Chebyshev Pseudospectral Collocation Method

Sun

Lü

Shen

et al. 2021

Ind. Eng. Chem. Res.

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ePC-SAFT-DFT is a powerful tool for studying the properties of confined ionic liquids for CO 2 separation, in which efficient algorithms are required to obtain the calculation efficiently. In this work, the feasibility of accelerating the ePC-SAFT-DFT calculation with the Chebyshev pseudo-spectral collocation method was discussed for the confined ionic liquid (IL)−CO 2 systems. In addition, a general scheme was proposed to search the electrical boundary potential. The new algorithm was further combined with the general scheme to model the confined IL−CO 2 systems. It was found that the Chebyshev pseudo-spectral collocation method can improve the efficiency of the ePC-SAFT-DFT calculation significantly. Moreover, the new algorithm can be further combined with the general scheme to efficiently describe the density profile of the IL−CO 2 system inside the electroneutral nanopores.

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An Efficient Algorithm for Molecular Density Functional Theory in Cylindrical Geometry: Application to Interfacial Statistical Associating Fluid Theory (iSAFT)

Cited by 14 publications

References 67 publications

Monte Carlo Molecular Simulation Study of Carbon Dioxide Sequestration into Dry and Wet Calcite Pores Containing Methane

Monte Carlo Molecular Simulation Study of Carbon Dioxide Sequestration into Dry and Wet Calcite Pores Containing Methane

Variation Free Approach for Molecular Density Functional Theory: Data-driven Stochastic Optimization

Accelerate the ePC-SAFT-DFT Calculation with the Chebyshev Pseudospectral Collocation Method

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