Calculations of Vibrational Energy Levels by Using a Hybrid ab Initio and DFT Quartic Force Field:  Application to Acetonitrile

Bégué, Didier; Carbonnière, Philippe; Pouchan, Claude

doi:10.1021/jp0406114

Cited by 131 publications

(132 citation statements)

References 60 publications

(88 reference statements)

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“…Likewise, we expect harmonic frequencies calculated at higher levels of theory-for instance, at the coupled-cluster level of theory-to perform well in combination with SCF anharmonic corrections; indeed, such an approach has been used in earlier works. 38,70,71 The BLYP results consistently show the poorest agreement with experiment. However, much of the discrepancy arises from inaccurate harmonic frequencies.…”

Section: Resultsmentioning

confidence: 89%

Analytic cubic and quartic force fields using density-functional theory

Ringholm

Jonsson

Bast

et al. 2014

The Journal of Chemical Physics

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A second-order perturbation theory route to vibrational averages and transition properties of molecules: General formulation and application to infrared and vibrational circular dichroism spectroscopies The Journal of Chemical Physics 136, 124108 (2012) We present the first analytic implementation of cubic and quartic force constants at the level of Kohn-Sham density-functional theory. The implementation is based on an open-ended formalism for the evaluation of energy derivatives in an atomic-orbital basis. The implementation relies on the availability of open-ended codes for evaluation of one-and two-electron integrals differentiated with respect to nuclear displacements as well as automatic differentiation of the exchange-correlation kernels. We use generalized second-order vibrational perturbation theory to calculate the fundamental frequencies of methane, ethane, benzene, and aniline, comparing B3LYP, BLYP, and Hartree-Fock results. The Hartree-Fock anharmonic corrections agree well with the B3LYP corrections when calculated at the B3LYP geometry and from B3LYP normal coordinates, suggesting that the inclusion of electron correlation is not essential for the reliable calculation of cubic and quartic force constants.

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Section: Resultsmentioning

confidence: 89%

Analytic cubic and quartic force fields using density-functional theory

Ringholm

Jonsson

Bast

et al. 2014

The Journal of Chemical Physics

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“…Unlike the second-order perturbation theory approach (hereafter PT2), which fails in the case of too strong anharmonic couplings, the variational treatment is exact while considering all the excitations of the vibrational levels of interest, for a given Hamiltonian. On the basis of our experience (see ref 8 and therein), configurations interaction (hereafter CI) of single, double, triple, and quadruple excitations yields a good estimation of the nature and the weight of vibrational configurations mixed in each vibrational state. This is the treatment considered here.…”

Section: Introductionmentioning

confidence: 99%

Fermi Resonances of Borohydrides in a Crystalline Environment of Alkali Metals

Carbonnière

Hagemann

2006

J. Phys. Chem. A

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Vibrational spectra of BH 4-and its isotopic analogues in a crystalline environment of alkali metals cations (K + , Rb + , Cs + ) have been investigated beyond the harmonic approximation using a variational approach supported by computations of B3LYP type anharmonic force fields. From the comparison of the observed and simulated IR spectra, the influence of the anharmonic couplings on the band position and on the relative intensity of the allowed vibrational transitions is discussed. Here, the effect of the crystalline environment induces a blue shift of about 50 and 100 cm -1 respectively for the bending and stretching modes of BH 4 -. Furthermore, anharmonic effects, which are exclusively well reproduced by a variational approach, are needed to yield reliable positions and relative amplitudes of IR allowed combination and overtone transitions. This leads to theoretical results fitting their experimental counterpart between 6 and 30 cm -1 in the investigated series.

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“…Ref. 82 gives force constants calculated with a hybrid coupled cluster/density functional theory method. They also report vibrational levels computed from subspaces determined with second order perturbation theory.…”

Section: Application To a 12-d Model For Acetonitrile (Ch3cn)mentioning

confidence: 99%

“…q 8 of Ref. 82). We use the J = 0 normal coordinate kinetic energy operator (KEO), but omit the π − π cross terms and the potential-like term,…”

Section: Application To a 12-d Model For Acetonitrile (Ch3cn)mentioning

confidence: 99%

Calculating vibrational spectra with sum of product basis functions without storing full-dimensional vectors or matrices

Leclerc

Carrington

2014

The Journal of Chemical Physics

120

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We propose an iterative method for computing vibrational spectra that significantly reduces the memory cost of calculations. It uses a direct product primitive basis, but does not require storing vectors with as many components as there are product basis functions. Wavefunctions are represented in a basis each of whose functions is a sum of products (SOP) and the factorizable structure of the Hamiltonian is exploited. If the factors of the SOP basis functions are properly chosen, wavefunctions are linear combinations of a small number of SOP basis functions. The SOP basis functions are generated using a shifted block power method. The factors are refined with a rank reduction algorithm to cap the number of terms in a SOP basis function. The ideas are tested on a 20-D model Hamiltonian and a realistic CH 3 CN (12 dimensional) potential. For the 20-D problem, to use a standard direct product iterative approach one would need to store vectors with about 10 20 components and would hence require about 8 × 10 11 GB. With the approach of this paper only 1 GB of memory is necessary. Results for CH 3 CN agree well with those of a previous calculation on the same potential.

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Calculations of Vibrational Energy Levels by Using a Hybrid ab Initio and DFT Quartic Force Field: Application to Acetonitrile

Cited by 131 publications

References 60 publications

Analytic cubic and quartic force fields using density-functional theory

Analytic cubic and quartic force fields using density-functional theory

Fermi Resonances of Borohydrides in a Crystalline Environment of Alkali Metals

Calculating vibrational spectra with sum of product basis functions without storing full-dimensional vectors or matrices

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