Improved modeling of anharmonicity for furan microsolvation

Kopp, Wassja A.; Mödden, Matthias L; Viswanathan, Narasimhan; Rath, Gabriel; Leonhard, Kai

doi:10.1039/d2cp03907a

Cited by 3 publications

(1 citation statement)

References 51 publications

(75 reference statements)

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“…Then, in TAMkin, 2000 basis functions were used to solve the 1D-HR Schroedinger Equation. Our in-house code TamkinTools [59] was used to obtain very smooth Fourier series fits to the potentials by not only minimizing the RMS deviation from the computed points but also minimizing the curvature. This lets us use Fourier series of higher order to obtain better fits while still avoiding oscillations.…”

Section: Computationsmentioning

confidence: 99%

Thermal decomposition of 1-ethyl-3-methylimidazolium acetate

Zaitsau

Papusha

Kopp

et al. 2023

Preprint

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To realize the potential applications of ionic liquids as working fluids and solvents one should have knowledge about their long-term stability, which depends on their thermally initiated decomposition. However, the possible decomposition pathways are not yet known accurately. 1-Ethyl-3-methylimidazolium acetate ([C2Mim][OAc]) is widely studied and shows potential in cellulose dissolution. In this study, we investigate possible [C2Mim][OAc] decomposition pathways by combining decomposition experiments and ab initio rate constant computations. Both approaches yield activation energies around 135 kJ·mol-1, which significantly deviate from earlier TGA measurements with open surface yielding 100 - 110 kJ·mol-1 and are probably affected by evaporation. Our study uses an improved TGA measurement protocol with a sealed pan with a tiny hole that fosters measurement of the actual chemical process leading to mass loss. Ab initio computations of this study comprise vapor-liquid equilibria of reactants and products as well as forward and reverse reaction rate constants in the gas and liquid phase. Calculations for the gas phase closely match a first-order analysis of the experiments, but calculations for the liquid phase strongly depend on the quality of solvation modeling. The computations indicate that the SN2 pathway with an activation energy of 140 kJ·mol-1 dominates thermal decomposition of [C2Mim][OAc].

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Section: Computationsmentioning

confidence: 99%

Thermal decomposition of 1-ethyl-3-methylimidazolium acetate

Zaitsau

Papusha

Kopp

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

Thermal decomposition of 1-ethyl-3-methylimidazolium acetate

Zaitsau,

Papusha,

Kopp

et al. 2023

Journal of Molecular Liquids

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Efficient Generation of Torsional Energy Profiles by Multifidelity Gaussian Processes for Hindered Rotor Corrections

Fleck,

Kopp,

Viswanathan

et al. 2024

J. Chem. Theory Comput.

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Accurate thermochemistry computations often require proper treatment of torsional modes. The one-dimensional hindered rotor model has proven to be a computationally efficient solution, given a sufficiently accurate potential energy surface. Methods that provide potential energies at various compromises of uncertainty and computational time demand can be optimally combined within a multifidelity treatment. In this study, we demonstrate how multifidelity modeling leads to (1) smooth interpolation along low-fidelity scan points with uncertainty estimates, (2) inclusion of high-fidelity data that change the energetic order of conformations, and (3) predicting best next-point calculations to extend an initial coarse grid. Our diverse application set comprises molecules, clusters, and transition states of alcohols, ethers, and rings. We discuss limitations for cases in which the low-fidelity computation is highly unreliable. Different features of the potential energy curve affect different quantities. To obtain "optimal" fits, we apply strategies ranging from simple minimization of deviations to developing an acquisition function tailored for statistical thermodynamics. Bayesian prediction of best next calculations can save a substantial amount of computation time for one-and multidimensional hindered rotors.

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Improved modeling of anharmonicity for furan microsolvation

Abstract: Computational benchmark data for complexes requires accurate models of anharmonic torsional motion. State-of-the-art hindered rotor treatments come with a number of difficulties, regarding discontinuities from badly converged points or coupling,...

Cited by 3 publications

References 51 publications

Thermal decomposition of 1-ethyl-3-methylimidazolium acetate

Thermal decomposition of 1-ethyl-3-methylimidazolium acetate

Thermal decomposition of 1-ethyl-3-methylimidazolium acetate

Efficient Generation of Torsional Energy Profiles by Multifidelity Gaussian Processes for Hindered Rotor Corrections

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