Multiple minima hypersurfaces of water clusters for calculations of association energy

Montero, Luis A.; Molina, José Molina; Fabian, Jürgen

doi:10.1002/1097-461x(2000)79:1<8::aid-qua2>3.0.co;2-0

Cited by 55 publications

(29 citation statements)

References 24 publications

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“…placed at the centre of a cube of defined side length, and extensively applied to study the microhydration and noncovalent interaction of molecular complexes. [38][39][40][41][42][43]…”

Section: Localisation Of Stationary Points On the Pes Of Carboxylic Amentioning

confidence: 99%

Density Functional Theory Study of the Oligomerization of Carboxylic Acids

Tommaso

Watson

2014

J. Phys. Chem. A

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We present a density functional theory [M06-2X/6-31+G(d,p)] study of the structures and free energies of formation of oligomers of four carboxylic acids (formic acid, acetic acid, tetrolic acid, and benzoic acid) in water, chloroform, and carbon tetrachloride. Solvation effects were treated using the SMD continuum solvation model. The low-lying energy structures of molecular complexes were located by adopting an efficient search procedure to probe the potential energy surfaces of the oligomers of carboxylic acids (CA)n (n = 2-6). The free energies of the isomers of (CA)n in solution were determined as the sum of the electronic energy, vibrational-rotational-translational gas-phase contribution, and solvation free energy. The assessment of the computational protocol adopted in this study with respect to the dimerization of acetic acid, (AA)2, and formic acid, (FA)2, located new isomers of (AA)2 and (FA)2 and gave dimerization constants in good agreement with the experimental values. The calculation of the self-association of acetic acid, tetrolic acid, and benzoic acid shows the following: (i) Classic carboxylic dimers are the most stable isomer of (CA)2 in both the gas phase and solution. (ii) Trimers of carboxylic acid are stable in apolar aprotic solvents. (iii) Molecular clusters consisting of two interacting classic carboxylic dimers (CA)4,(D+D) are the most stable type of tetramers, but their formation from the self-association of classic carboxylic dimers is highly unfavorable. (iv) For acetic acid and tetrolic acid the reactions (CA)2 + 2CA → (CA)4,(D+D) and (CA)3 + CA → (CA)4,(D+D) are exoergonic, but these aggregation pathways go through unstable clusters that could hinder the formation of tetrameric species. (v) For tetrolic acid the prenucleation species that are more likely to form in solution are dimeric and trimeric structures that have encoded structural motifs resembling the α and β solid forms of tetrolic acid. (vi) Stable tetramers of benzoic acid could form in carbon tetrachloride from the aggregation of trimers and monomers. (vii) Higher order clusters such as acetic acid pentamers and tetrolic acid hexamers are highly unstable in all solvation environments.

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“…placed at the centre of a cube of defined side length, and extensively applied to study the microhydration and noncovalent interaction of molecular complexes. [38][39][40][41][42][43]…”

Section: Localisation Of Stationary Points On the Pes Of Carboxylic Amentioning

confidence: 99%

Density Functional Theory Study of the Oligomerization of Carboxylic Acids

Tommaso

Watson

2014

J. Phys. Chem. A

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“…More structures only add redundant structures and rarely a change in the statistically averaged internal energy. It has also been published earlier 16, 19, 26.…”

Section: Systems and Computational Detailsmentioning

confidence: 84%

“…For hydration effects, the MMH approach was used. It has been described previously in detail 16, 17. A minimum of 50 random molecular clusters formed by solute and solvent molecules have been built in every case.…”

Section: Systems and Computational Detailsmentioning

confidence: 99%

“…The multiple minima hypersurfaces (MMH) approach estimate association energies of the molecular ground states combining semiempirical QM method and statistical thermodynamics formulae 16, 17. Applications to several objects of this method are being recently published 18–20, including hydration clusters of silicates, drugs, and water 16, 17, 20.…”

Section: Introductionmentioning

confidence: 99%

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Multiple minima hypersurfaces studies of aluminosilicate hydration

Pérez-Badell

Montero

2009

Int J of Quantum Chemistry

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Hydrothermal zeolite synthesis is a complex process that is difficult toanalyze experimentally. In this work, the role of water as solvent on the formation of aluminate and aluminosilicate clusters is described by quantum chemical calculations. The multiple minima hypersurfaces approach was used. It combines quantum chemical Hamiltonians for the calculation of the internal energy with statistical modeling and formulae for the calculation of thermodynamic functions of association. The structures of most probable hydration clusters are proposed and some of their association properties are calculated. Ab initio and semiempirical calculations of the structures and relevant reactions of aluminate and aluminosilicate fragments were reported. The results could be employed for an interpretation of the aluminosilicate synthesis. Calculations demonstrate the importance of considering other than the deepest minimum structures, giving a significant role to consider entropy of association.

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“…The Multiple Minimum Hypersurfaces (MMH) approach allows us to study the collective effects of the molecular environment by combining the quantum and mechanical procedures for the calculation of the molecular aggregate energies with statistical thermodynamics for the determination of the thermodynamic properties of association of polyatomic systems [18]. This methodology explores the potential energy surface to find the molecular arrangements, with their respective geometries and energies, that group the most important significant states for the calculation of the thermodynamic properties of the complete system [19].…”

Section: Study Of Molecular Interactions Using the Mmh Methodologymentioning

confidence: 99%

Water-In-Oil Emulsions through Porous Media and the Effect of Surfactants: Theoretical Approaches

et al. 2019

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The most complex components in heavy crude oils tend to form aggregates that constitute the dispersed phase in these fluids, showing the high viscosity values that characterize them. Water-in-oil (W/O) emulsions are affected by the presence and concentration of this phase in crude oil. In this paper, a theoretical study based on computational chemistry was carried out to determine the molecular interaction energies between paraffin-asphaltenes-water and four surfactant molecules to predict their effect in W/O emulsions and the theoretical influence on the pressure drop behavior for fluids that move through porous media. The mathematical model determined a typical behavior of the fluid when the parameters of the system are changed (pore size, particle size, dispersed phase fraction in the fluid, and stratified fluid) and the viscosity model determined that two of the surfactant molecules are suitable for applications in the destabilization of W/O emulsions. Therefore, an experimental study must be set to determine the feasibility of the methodology and mathematical model displayed in this work.

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Multiple minima hypersurfaces of water clusters for calculations of association energy

Cited by 55 publications

References 24 publications

Density Functional Theory Study of the Oligomerization of Carboxylic Acids

Density Functional Theory Study of the Oligomerization of Carboxylic Acids

Multiple minima hypersurfaces studies of aluminosilicate hydration

Water-In-Oil Emulsions through Porous Media and the Effect of Surfactants: Theoretical Approaches

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