High Level ab Initio Energies and Structures for the Rotamers of 1,3-Butadiene

Feller, David; Craig, Norman C.

doi:10.1021/jp8095709

Cited by 55 publications

(117 citation statements)

References 53 publications

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“…The Role of the AGP Ansatz on the Electronic Correlation of 1,3-Butadiene. To make a comparison between our VMC structures and that obtained through CCSD(T)/CBS, 10 it is essential to clarify the stability of the VMC results. For this purpose, we have done different calculations with the basis sets described in Table 1, and with the atomic JAGP and the molecular JSD ansaẗze described in the Computational Methods.…”

Section: Resultsmentioning

confidence: 99%

π-Conjugation in trans-1,3-Butadiene: Static and Dynamical Electronic Correlations Described through Quantum Monte Carlo

Barborini

Guidoni

2015

J. Chem. Theory Comput.

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We investigate the effects of the static and dynamical electronic correlations on the level of conjugation of the trans-1,3-butadiene molecule through Quantum Monte Carlo methods applied to an Antisymmetrized Geminal Power (AGP) wave function, with a Jastrow factor similar to the Gutzwiller ansatz. The degree of conjugation is measured through the convergence of the structural properties of 1,3-butadiene and in particular of the Bond Length Alternation (BLA), that is the difference between the lengths of the single and double carbon bonds. After verifying the different roles of the Fermionic AGP part of our wave function and of the Jastrow factor in recovering electronic correlation, we study the effects of a constrained Active Space AGP (AGPAS), similar to that used in the Complete Active Space (CAS) representation. Through this AGPAS, we are able to identify the effect of the limited active space on the degree of conjugation, showing that in the limit of infinite active space the structural properties converge exactly to those of the atomic AGP, giving a BLA for 1,3-butadiene around 0.1244(5) Å.

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Section: Resultsmentioning

confidence: 99%

π-Conjugation in trans-1,3-Butadiene: Static and Dynamical Electronic Correlations Described through Quantum Monte Carlo

Barborini

Guidoni

2015

J. Chem. Theory Comput.

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“…(Note that bigger CASSCF active spaces [46] and highly correlated methods [47] have suggested that the planar C 2v BD geometry is unstable with respect to deformation of the central bond backbone dihedral and that the local minimum corresponds to a distorted structure. As the differences in electronic character between electronic states are more marked in the symmetric geometry and can be given a symmetry label, we will consider a C 2v initial BD structure as the FC geometry.…”

Section: Computational Detailsmentioning

confidence: 99%

Photochemical reaction paths of cis-dienes studied with RASSCF: the changing balance between ionic and covalent excited states

et al. 2015

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(2015) Photochemical reaction paths of cis-dienes studied with RASSCF: the changing balance between ionic and covalent excited states, Molecular Physics, 113:13-14, 1978-1990, DOI: 10.1080/00268976.2015 Physics, 2015 Vol. 113, Nos. 13-14, 1978-1990 The balanced description of ionic and covalent molecular excited electronic states still presents a challenge for current electronic structure methods. In this contribution, we show how the restricted active space self-consistent field (RASSCF) method can be used to address this problem, applied to two dienes in the cis conformation. As with the closely related complete active space self-consistent field (CASSCF) method, the construction of the orbital active space in the RASSCF methodology requires the a priori formulation of a physical or theoretical model of the system being studied. In this article, we discuss how the active space can be constructed in a guided and systematic way, using pairs of natural bond orbitals as correlating partner orbitals (oscillator orbitals) and semi-internal correlation. The resulting balanced description of the covalent and ionic valence excited states -with the ionic state correctly lower in energy at the Franck-Condon geometryis suitable to study the photochemistry of these and other molecules.

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“…[15][16][17][18][19][20][21][22][23][24][25][26][27] Thea dvent of modern electronic structure methods [28][29][30] and careful examination of gas-phase Raman spectra [31] have led to the prevailing view that cisbutadiene is in fact gauche. [32][33][34][35] Despite this progress, conclusive detection and structural characterization of this elementary molecule have remained elusive for sixty years. [36,37] Herein we report the first microwave spectrum of "cis" butadiene,w hich unambiguously shows that it possesses an onplanar gauche structure.T he experimental evidence for non-planarity,w hich includes not only an early complete equilibrium structure but also vivid observation of tunneling between equivalent gauche minima, was acquired with ac ombination of sensitive microwave techniques and high accuracy ab initio calculations.Examination of the structures and energetics obtained from both experiment and theory reveals detailed information about how the interplay of steric and conjugation effects determines the structure of this fundamental reaction intermediate.…”

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confidence: 99%

The Molecular Structure of gauche‐1,3‐Butadiene: Experimental Establishment of Non‐planarity

et al. 2018

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The planarity of the second stable conformer of 1,3-butadiene, the archetypal diene for the Diels-Alder reaction in which a planar conjugated diene and a dienophile combine to form a ring, is not established. The most recent high level calculations predicted the species to adopt a twisted, gauche structure owing to steric interactions between the inner terminal hydrogens rather than a planar, cis structure favored by the conjugation of the double bonds. The structure cis-1,3-butadiene is unambiguously confirmed experimentally to indeed be gauche with a substantial dihedral angle of 34°, in excellent agreement with theory. Observation of two tunneling components indicates that the molecule undergoes facile interconversion between two equivalent enantiomeric forms. Comparison of experimentally determined structures for gauche- and trans-butadiene provides an opportunity to examine the effects of conjugation and steric interactions.

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High Level ab Initio Energies and Structures for the Rotamers of 1,3-Butadiene

Cited by 55 publications

References 53 publications

π-Conjugation in trans-1,3-Butadiene: Static and Dynamical Electronic Correlations Described through Quantum Monte Carlo

π-Conjugation in trans-1,3-Butadiene: Static and Dynamical Electronic Correlations Described through Quantum Monte Carlo

Photochemical reaction paths of cis-dienes studied with RASSCF: the changing balance between ionic and covalent excited states

The Molecular Structure of gauche‐1,3‐Butadiene: Experimental Establishment of Non‐planarity

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