Methane Adsorption on Heteroatom-Modified Maquettes of Porous Carbon Surfaces

<div> <div> <div> <p>Experimental studies and theoretical models presently disagree on methane adsorption energetics on carbon materials that include crystalline graphene-like structures to amorphous materials with or without significant edge structure. However, this information is critical for the rational design and optimization of the structure and composition of adsorbents for natural gas storage. The delicate nature of the interactions inherent to methane physisorption, such as dispersion interactions, polarization of both the adsorbent and the adsorbate, interplay between H- bonding and tetrel bonding, and induced dipole/Coulomb interactions, requires computational treatment at the highest possible level of theory while remaining non-prohibitive in terms of computational cost. In this study, we employ the smallest reasonable computational model, a maquette, of porous carbon surfaces with a central atomic binding site for substitution. The most accurate predictions of the methane adsorption energetics were achieved by electron-correlated molecular orbital theory (CCSD(T)) and hybrid density functional theory (MN15) calculations, both employing a saturated all-electron basis set. The characteristic geometry of methane adsorption on a carbon surface was likened to a “lander” position over the ring centers of the adsorbent. This adsorbate/adsorbent arrangement arises due to bonding interactions of the adsorbent π-system with the proximal H–C bonds of methane, in addition to tetrel bonding between the antibonding orbital of the distal C–H bond and the central atom of the maquette (C, B, or N). The polarization of the electron density as well as structural deformations in both the adsorbate and adsorbent molecules clearly indicate a ~3 kJ mol-1 preference for methane binding on the N-substituted maquette. In this study, the B-substituted maquette showed a comparable or lower binding energy than the unsubstituted, pure C model, depending on the level of theory employed. The calculated thermodynamic results indicate an unambiguous guiding strategy toward incorporating electron- enriched substitutions (e.g., N) in carbon materials as a way to increase methane storage capacity over electron deficient (e.g., B) modifications. The thermochemical calculation methodologies were critically evaluated in order to establish a conceptual agreement between the experimental isosteric heat of adsorption and the binding enthalpies/free energies from statistical thermodynamics principles. </p> </div> </div> </div>

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Evaluating Transition Metal Barrier Heights with the Latest DFT Exchange–Correlation Functionals – the MOBH35 Benchmark Dataset

10.26434/chemrxiv.7732262.v1 ◽

2019 ◽

Author(s):

Mark Iron ◽

Trevor Janes

Keyword(s):

Transition Metal ◽

Density Functional ◽

Computational Cost ◽

Basis Set ◽

Functional Theory ◽

Exchange Correlation ◽

Barrier Heights ◽

Complete Basis Set ◽

Complete Basis Set Limit ◽

Hybrid Functionals

A new database of transition metal reaction barrier heights – MOBH35 – is presented. Benchmark energies (forward and reverse barriers and reaction energy) are calculated using DLPNO-CCSD(T) extrapolated to the complete basis set limit using a Weizmann1-like scheme. Using these benchmark energies, the performance of a wide selection of density functional theory (DFT) exchange–correlation functionals, including the latest from the Truhlar and Head-Gordon groups, is evaluated. It was found, using the def2-TZVPP basis set, that the ωB97M-V (MAD 1.8 kcal/mol), ωB97X-V (MAD 2.1 kcal/mol) and SCAN0 (MAD 2.1 kcal/mol) hybrid functionals are recommended. The double-hybrid functionals PWPB95 (MAD 1.6 kcal/mol) and B2K-PLYP (MAD 1.8 kcal/mol) did perform slightly better but this has to be balanced by their increased computational cost.

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Accurate quadruple-ζ basis-set approximation for double-hybrid density functional theory with an order of magnitude reduction in computational cost

Theoretical Chemistry Accounts ◽

10.1007/s00214-013-1426-9 ◽

2013 ◽

Vol 133 (2) ◽

Cited By ~ 18

Author(s):

Bun Chan ◽

Leo Radom

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Computational Cost ◽

Basis Set ◽

Hybrid Density Functional Theory ◽

Functional Theory ◽

Order Of Magnitude ◽

Set Approximation ◽

Hybrid Density Functional

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Accuracy and Reliability in the Simulation of Vibrational Spectra: A Comprehensive Benchmark of Energies and Intensities Issuing From Generalized Vibrational Perturbation Theory to Second Order (GVPT2)

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2021.665232 ◽

2021 ◽

Vol 8 ◽

Author(s):

Qin Yang ◽

Marco Mendolicchio ◽

Vincenzo Barone ◽

Julien Bloino

Keyword(s):

Perturbation Theory ◽

Electronic Structure ◽

Density Functional ◽

Computational Cost ◽

Theoretical Data ◽

Infrared Region ◽

Second Order ◽

Basis Set ◽

Molecular Systems ◽

The Impact

Vibrational spectroscopy represents an active frontier for the identification and characterization of molecular species in the context of astrochemistry and astrobiology. As new missions will provide more data over broader ranges and at higher resolution, especially in the infrared region, which could be complemented with new spectrometers in the future, support from laboratory experiments and theory is crucial. In particular, computational spectroscopy is playing an increasing role in deepening our understanding of the origin and nature of the observed bands in extreme conditions characterizing the interstellar medium or some planetary atmospheres, not easily reproducible on Earth. In this connection, the best compromise between reliability, feasibility and ease of interpretation is still a matter of concern due to the interplay of several factors in determining the final spectral outcome, with larger molecular systems and non-covalent complexes further exacerbating the dichotomy between accuracy and computational cost. In this context, second-order vibrational perturbation theory (VPT2) together with density functional theory (DFT) has become particularly appealing. The well-known problem of the reliability of exchange-correlation functionals, coupled with the treatment of resonances in VPT2, represents a challenge for the determination of standardized or “black-box” protocols, despite successful examples in the literature. With the aim of getting a clear picture of the achievable accuracy and reliability of DFT-based VPT2 calculations, a multi-step study will be carried out here. Beyond the definition of the functional, the impact of the basis set and the influence of the resonance treatment in VPT2 will be analyzed. For a better understanding of the computational aspects and the results, a short summary of vibrational perturbation theory and the overall treatment of resonances for both energies and intensities will be given. The first part of the benchmark will focus on small molecules, for which very accurate experimental and theoretical data are available, to investigate electronic structure calculation methods. Beyond the reliability of energies, widely used for such systems, the issue of intensities will also be investigated in detail. The best performing electronic structure methods will then be used to treat larger molecular systems, with more complex topologies and resonance patterns.

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THEORETICAL STUDIES ON BOND DISSOCIATION ENERGIES FOR SOME THIOL COMPOUNDS BY DENSITRY FUNCTIONAL THEORY AND CBS-Q METHOD

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633608004258 ◽

2008 ◽

Vol 07 (05) ◽

pp. 943-951 ◽

Cited By ~ 2

Author(s):

XIAO-HONG LI ◽

ZHENG-XIN TANG ◽

ABRAHAM F. JALBOUT ◽

XIAN-ZHOU ZHANG ◽

XIN-LU CHENG

Keyword(s):

Density Functional ◽

Computational Cost ◽

Basis Set ◽

Basis Sets ◽

Q Method ◽

Bond Dissociation Energies ◽

Functional Theory ◽

Thiol Compounds ◽

Bond Dissociation ◽

Dissociation Energies

Quantum chemical calculations are used to estimate the bond dissociation energies (BDEs) for 15 thiol compounds. These compounds are studied by employing the hybrid density functional theory (B3LYP, B3PW91, B3P86, PBE0) methods and the complete basis set (CBS-Q) method together with 6-311G** basis set. It is demonstrated that B3P86 and CBS-Q methods are accurate for computing the reliable BDEs for thiol compounds. In order to test whether the non-local BLYP method suggested by Fu et al.19 is general for our study and whether B3P86 method has a low basis set sensitivity, the BDEs for seven thiol compounds are also calculated using BLYP/6-31+G* and B3P86 method with 6-31+G*, 6-31+G**, and 6-311+G** basis sets for comparison. The obtained results are compared with the available experimental results. It is noted that B3P86 method is not sensitive to the basis set. Considering the inevitable computational cost of CBS-Q method and the reliability of the B3P86 calculations, B3P86 method with a moderate or a larger basis set may be more suitable to calculate the BDEs of the C–SH bond for thiol compounds.

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The Near Edge Structure of Hexagonal Boron Nitride

Microscopy and Microanalysis ◽

10.1017/s1431927614000737 ◽

2014 ◽

Vol 20 (4) ◽

pp. 1053-1059 ◽

Cited By ~ 14

Author(s):

Nicholas L. McDougall ◽

Rebecca J. Nicholls ◽

Jim G. Partridge ◽

Dougal G. McCulloch

Keyword(s):

Boron Nitride ◽

Density Functional ◽

Light Emission ◽

Hexagonal Boron Nitride ◽

Core Loss ◽

Experimental Studies ◽

Stacking Faults ◽

Edge Structure ◽

Deep Ultraviolet ◽

Electron Energy Loss

AbstractHexagonal boron nitride (hBN) is a promising material for a range of applications including deep-ultraviolet light emission. Despite extensive experimental studies, some fundamental aspects of hBN remain unknown, such as the type of stacking faults likely to be present and their influence on electronic properties. In this paper, different stacking configurations of hBN are investigated using CASTEP, a pseudopotential density functional theory code. AB-b stacking faults, in which B atoms are positioned directly on top of one another while N atoms are located above the center of BN hexagons, are shown to be likely in conventional AB stacked hBN. Bandstructure calculations predict a single direct bandgap structure that may be responsible for the discrepancies in bandgap type observed experimentally. Calculations of the near edge structure showed that different stackings of hBN are distinguishable using measurements of core-loss edges in X-ray absorption and electron energy loss spectroscopy. AB stacking was found to best reproduce features in the experimental B and N K-edges. The calculations also show that splitting of the 1s to π* peak in the B K-edge, recently observed experimentally, may be accounted for by the presence of AB-b stacking faults.

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Evaluating Transition Metal Barrier Heights with the Latest DFT Exchange–Correlation Functionals – the MOBH35 Benchmark Dataset

10.26434/chemrxiv.7732262.v2 ◽

2019 ◽

Author(s):

Mark Iron ◽

Trevor Janes

Keyword(s):

Transition Metal ◽

Density Functional ◽

Computational Cost ◽

Basis Set ◽

Functional Theory ◽

Exchange Correlation ◽

Barrier Heights ◽

Complete Basis Set ◽

Complete Basis Set Limit ◽

Hybrid Functionals

A new database of transition metal reaction barrier heights – MOBH35 – is presented. Benchmark energies (forward and reverse barriers and reaction energy) are calculated using DLPNO-CCSD(T) extrapolated to the complete basis set limit using a Weizmann1-like scheme. Using these benchmark energies, the performance of a wide selection of density functional theory (DFT) exchange–correlation functionals, including the latest from the Truhlar and Head-Gordon groups, is evaluated. It was found, using the def2-TZVPP basis set, that the ωB97M-V (MAD 1.8 kcal/mol), ωB97X-V (MAD 2.1 kcal/mol) and SCAN0 (MAD 2.1 kcal/mol) hybrid functionals are recommended. The double-hybrid functionals PWPB95 (MAD 1.6 kcal/mol) and B2K-PLYP (MAD 1.8 kcal/mol) did perform slightly better but this has to be balanced by their increased computational cost.

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Rational design of a molecularly imprinted polymer for dinotefuran: theoretical and experimental studies aimed at the development of an efficient adsorbent for microextraction by packed sorbent

The Analyst ◽

10.1039/c7an01324h ◽

2018 ◽

Vol 143 (1) ◽

pp. 141-149 ◽

Cited By ~ 19

Author(s):

Camilla Fonseca Silva ◽

Keyller Bastos Borges ◽

Clebio Soares do Nascimento

Keyword(s):

Molecularly Imprinted Polymer ◽

Density Functional ◽

Rational Design ◽

Experimental Studies ◽

Density Functional Theory Calculations ◽

Imprinted Polymer ◽

Functional Theory ◽

Molecularly Imprinted ◽

Functional Monomers ◽

Packed Sorbent

In this work, we studied theoretically the formation process of a molecularly imprinted polymer (MIP) for dinotefuran (DNF), by testing distinct functional monomers (FM) in various solvents through density functional theory calculations.

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Investigating magnetic properties of Co68Fe4B15Si13 amorphous alloy by molecular dynamics and DFT calculations

Modern Physics Letters B ◽

10.1142/s0217984917500944 ◽

2017 ◽

Vol 31 (09) ◽

pp. 1750094

Author(s):

R. Mardani ◽

M. R. Kazerani ◽

H. Shahmirzaee

Keyword(s):

Molecular Dynamics ◽

Magnetic Properties ◽

Amorphous Alloys ◽

Density Functional ◽

Rational Design ◽

Wide Spectrum ◽

Dipole Moments ◽

Experimental Studies ◽

Functional Theory ◽

Electronic And Magnetic Properties

Cobalt-based amorphous alloys, in particular CoFeBSi, have been widely used to study the response of ac-impedance to the external dc magnetic field, i.e., the so-called Giant Magneto Impedance (GMI) effect. The utility of CoFeBSi in different applications such as field-sensitive sensors is known and practiced. Despite the wealth of experimental studies on GMI properties of CoFeBSi alloys, no computational approach has yet been addressed on electronic and magnetic properties of these systems at nanoscales. In this study, we have computed electronic and magnetic properties of amorphous CoFeBSi alloys using a combined Molecular Dynamics (MD) and Density Functional Theory (DFT) approach. MD is used to provide a physically realistic sampling of different atomic configurations while the properties such as dipole moments and magnetic susceptibilities are computed using DFT. Our study shows a wide spectrum of electronic as well as magnetic properties for nanoclusters of different sizes having implications for rational design of Co-based ferromagnetic alloys.

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