Accurate Coupled Cluster Calculations of the Reaction Barrier Heights of Two CH3• + CH4 Reactions

Klopper, Wim; Bachorz, Rafał A.; Tew, David P.; Aguilera-Iparraguirre, Jorge; Carissan, Yannick; Hättig, Christof

doi:10.1021/jp902753s

Cited by 12 publications

(11 citation statements)

References 63 publications

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“…These properties have allowed it to be successfully applied in all sorts of fields, including thermochemistry and kinetics. [32][33][34][35][36] CBS-QB3 has previously been used in a variety of kinetic studies, including some relevant to sulfur chemistry, and the reaction barriers calculated have been shown to have an uncertainty of a few kcal mol À1 . 22,23,37,38 CBS-QB3 thermochemistry is usually more accurate due to the availability of empirical Bond Additivity Corrections (BAC).…”

Section: Methodsmentioning

confidence: 99%

A kinetic and thermochemical database for organic sulfur and oxygen compounds

Class

Aguilera-Iparraguirre

Green

2015

Phys. Chem. Chem. Phys.

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Potential energy surfaces and reaction kinetics were calculated for 40 reactions involving sulfur and oxygen. This includes 11 H2O addition, 8 H2S addition, 11 hydrogen abstraction, 7 beta scission, and 3 elementary tautomerization reactions, which are potentially relevant in the combustion and desulfurization of sulfur compounds found in various fuel sources. Geometry optimizations and frequencies were calculated for reactants and transition states using B3LYP/CBSB7, and potential energies were calculated using CBS-QB3 and CCSD(T)-F12a/VTZ-F12. Rate coefficients were calculated using conventional transition state theory, with corrections for internal rotations and tunneling. Additionally, thermochemical parameters were calculated for each of the compounds involved in these reactions. With few exceptions, rate parameters calculated using the two potential energy methods agreed reasonably, with calculated activation energies differing by less than 5 kJ mol(-1). The computed rate coefficients and thermochemical parameters are expected to be useful for kinetic modeling.

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Section: Methodsmentioning

confidence: 99%

A kinetic and thermochemical database for organic sulfur and oxygen compounds

Class

Aguilera-Iparraguirre

Green

2015

Phys. Chem. Chem. Phys.

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“…Coupled-cluster (CC) theory has been used successfully for studying electron-electron correlation in many-electron systems. [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] In the context of multicomponent systems, the CC ansatz provides a balanced framework for a size-consistent and size-extensive treatment of many-particle correlation. Application of CC to excitons has been demonstrated earlier by Sundholm et al 36 and Vänskä et al 37 for a two-band effective mass approximation Hamiltonian model.…”

Section: Introductionmentioning

confidence: 99%

Development of the Multicomponent Coupled-Cluster Theory for Investigation of Multiexcitonic Interactions

Ellis

Aggarwal²,

Chakraborty

2015

J. Chem. Theory Comput.

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Multicomponent systems are defined as chemical systems that require a quantum mechanical description of two or more different types of particles. Non-Born-Oppenheimer electron-nuclear interactions in molecules, electron-hole interactions in electronically excited nanoparticles, and electron-positron interactions are examples of physical systems that require a multicomponent quantum mechanical formalism. The central challenge in the theoretical treatment of multicomponent systems is capturing the many-body correlation effects that exist not only between particles of identical types (electron-electron) but also between particles of different types (electron-nuclear and electron-hole). In this work, the development and implementation of multicomponent coupled-cluster (mcCC) theory for treating particle-particle correlation in multicomponent systems are presented. This method provides a balanced treatment of many-particle correlation effects in a general multicomponent system while maintaining a size-consistent and size-extensive formalism. The coupled-cluster ansatz presented here is an extension of the electronic structure CCSD formulation for multicomponent systems and is defined as |ΨmcCC⟩ = eT1I+T2I+T1II+T2II+T11I,II+T12I,II+T21I,II+T22I,II|0I0II⟩. The cluster amplitudes in the mcCC wave function were obtained by projecting the mcCC Schrödinger equation onto a direct product space of singly and doubly excited states of type I and II particles and then solving the resulting mcCC equations iteratively. These equations were derived using an automated application of the generalized Wick’s theorem and were implemented using a computer-assisted source code generation approach. The applicability of the mcCC method was demonstrated by calculating ground state energies of multicomponent Hooke's atom and positronium hydride systems as well as by calculating exciton and biexciton binding energies in multiexcitonic systems. For each case, the mcCC results were benchmarked against full configuration interaction (FCI) calculations and were found to be in excellent agreement with the FCI results. The effect of neglecting certain classes of multicomponent connected excitation terms from the mcCC wave function was also investigated. The results from this study demonstrate that connected cluster operators that generate simultaneous excitation in type I and type II space are critical for capturing electron-hole correlation in multiexcitonic systems.

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“…In these methods, the coulomb cusp, which is responsible for the slow convergence of the correlation energy in Gaussian basis sets, is explicitly parameterized into the wave function. Therefore, the F12 models like MP2‐F12 or CCSD(T)(F12) converge significantly faster to the CBS limit compared to the original models …”

Section: Introductionmentioning

confidence: 99%

New accurate benchmark energies for large water clusters: DFT is better than expected

Anacker

Friedrich

2014

J Comput Chem

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In this work, we use MP2 and coupled-cluster with single, double, and perturbative triple excitations [CCSD(T)] as well as their corresponding explicitly correlated (F12) counterparts to compute the interaction energies of water icosamers. The incremental scheme is used to compute benchmark energies at the CCSD(T)/CBS(45) and CCSD(T)(F12*)/cc-pVQZ-F12 level of theory. The four structures, dodecahedron, edge sharing, face sharing, and fused cubes, are part of the WATER27 test set and therefore, highly accurate interaction energies are required. All methods applied in this work lead to new benchmark energies for these four systems. To obtain these values, we carefully analyze the convergence of the interaction energies with respect to the basis set. Furthermore, we investigate the influence of the basis set superposition error and the core-valence correlation. The interaction energies are: dodecahedron -198.6 kcal/mol, edge sharing -209.7 kcal/mol, face sharing -208.0 kcal/mol, and fused cubes -208.0 kcal/mol. For water clusters, we recommend to use the PW6B95 density functional of Truhlar in combination with Grimme's dispersion correction (D3), as the mean absolute error is 0.9 and the root mean-squared deviation is only 1.4 kcal/mol.

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Accurate Coupled Cluster Calculations of the Reaction Barrier Heights of Two CH₃^• + CH₄ Reactions

Cited by 12 publications

References 63 publications

A kinetic and thermochemical database for organic sulfur and oxygen compounds

A kinetic and thermochemical database for organic sulfur and oxygen compounds

Development of the Multicomponent Coupled-Cluster Theory for Investigation of Multiexcitonic Interactions

New accurate benchmark energies for large water clusters: DFT is better than expected

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