General Perturb-Then-Diagonalize Model for the Vibrational Frequencies and Intensities of Molecules Belonging to Abelian and Non-Abelian Symmetry Groups

Mendolicchio, Marco; Bloino, Julien; Barone, Vincenzo

doi:10.1021/acs.jctc.1c00240

Cited by 25 publications

(22 citation statements)

References 145 publications

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“…The results of VPT2 calculations for these two molecules are provided in the Tables S9–S11. For these calculations, we utilize the deperturb and diagonalize approach, ,,, where states are considered to be nearly degenerate when their contribution to the wave function at any order exceeds 0.3. For HOH this criterion identifies the 2:2 Darling–Dennison resonance between the two OH stretches, while for HOD it identifies a 2:1 Fermi resonance between the HOD bend and the OD stretch.…”

Section: Resultsmentioning

confidence: 99%

Exploring Expansions of the Potential and Dipole Surfaces Used for Vibrational Perturbation Theory

McCoy

Boyer

2022

J. Phys. Chem. A

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A scheme for evaluating expansions of the potential and dipole moment surfaces for vibrational perturbation theory is described. The approach is based on numerical differentiation of the Hessian in the coordinates of interest. It is shown that performing these calculations in internal coordinates generates expansions that are transferable among isotopologues of the molecule of interest. Additionally, re-expressing the expansion of the potential in terms of functions of the internal coordinates, for example, cosines of angles or exponential functions of the bond length displacements, provides expansions that can be used for higher-order perturbation theory calculations. The approach is explored and the results are discussed for water, HOD, ammonia, isomers of HNO3, and halogenated methane.

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Section: Resultsmentioning

confidence: 99%

Exploring Expansions of the Potential and Dipole Surfaces Used for Vibrational Perturbation Theory

McCoy

Boyer

2022

J. Phys. Chem. A

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“…The derivation of the relative equations is rather cumbersome, and complete formulas were proposed by Rosnik and Polik for most common transitions considered in VPT2 calculations involving up to four quanta of difference, later reviewed by Krasnoshchekov et al and Douberly and co-workers . A generalization to non-Abelian symmetry groups was recently achieved for transitions up to two quanta . Darling–Dennison terms are normally added after the actual VPT2 calculations through a tailored variational step described later.…”

Section: Theorymentioning

confidence: 99%

An Effective and Automated Processing of Resonances in Vibrational Perturbation Theory Applied to Spectroscopy

Yang

Bloino

2022

J. Phys. Chem. A

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The broader availability of cost-effective methodologies like second-order vibrational perturbational theory (VPT2), also in general-purpose quantum chemical programs, has made the inclusion of anharmonic effects in vibrational calculations easier, paving the way to more accurate simulations. Combined with modern computing hardware, VPT2 can be used on relatively complex molecular systems with dozen of atoms. However, the problem of resonances and their corrections remains a critical pitfall of perturbative methods. Recent works have highlighted the sensitivity of band intensities to even subtle resonance effects, underlying the importance of a correct treatment to predict accurate spectral bandshapes. This aspect is even more critical with chiroptical spectroscopies whose signal is weak. This has motivated the present work in exploring robust methods and criteria to identify resonances not only in energy calculations but also on the transition moments. To study their performance, three molecules of representative sizes ranging from ten to several dozens of atoms were chosen. The impact of resonances, as well as the accuracy achievable once they are properly treated, is illustrated by the changes in spectral bandshapes, including chiroptical spectroscopies.

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“…Subsequently, the DFT cubic and semidiagonal quartic force constants have been combined with the CCSD(T)/(CBS+CV) MP2 quadratic force constants (harmonic wavenumbers), thus leading to hybrid CC/DFT approaches. The correspondence between the normal modes description of different QC models was checked by the visual inspection of molecular vibrations and the computations of “Duschinsky-like” matrices. − Finally, second-order vibrational perturbation theory (VPT2), , within the generalized GVPT2 model, − has been applied to the hybrid and DFT anharmonic force fields to evaluate anharmonic zero-point vibrational energy, wavenumbers and IR intensities. Standard criteria for anharmonic resonances have been employed, as suggested in the literature …”

Section: Computational Detailsmentioning

confidence: 99%

Structural and Vibrational Properties of Amino Acids from Composite Schemes and Double-Hybrid DFT: Hydrogen Bonding in Serine as a Test Case

et al. 2021

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The structures, relative stabilities, and vibrational wavenumbers of the two most stable conformers of serine, stabilized by the O−Hhydrogen bonds, have been evaluated by means of state-of-the-art composite schemes based on coupled-cluster (CC) theory. The socalled "cheap" composite approach (CCSD(T)/(CBS+CV) MP2 ) allowed determination of accurate equilibrium structures and harmonic vibrational wavenumbers, also pointing out significant corrections beyond the CCSD(T)/cc-pVTZ level. These accurate results stand as a reference for benchmarking selected hybrid and double-hybrid, dispersion-corrected DFT functionals. B2PLYP-D3 and DSDPBEP86 in conjunction with a triple-ζ basis set have been confirmed as effective methodologies for structural and spectroscopic studies of medium-sized flexible biomolecules, also showing intramolecular hydrogen bonding. These best performing double-hybrid functionals have been employed to simulate IR spectra by means of vibrational perturbation theory, also considering hybrid CC/DFT schemes. The best overall agreement with experiment, with mean absolute error of 8 cm −1 , has been obtained by combining CCSD(T)/(CBS +CV) MP2 harmonic wavenumbers with B2PLYP-D3/maug-cc-pVTZ anharmonic corrections. Finally, a composite scheme entirely based on CCSD(T) calculations (CCSD(T)/CBS+CV) has been employed for energetics, further confirming that serine II is the most stable conformer, also when zero-point vibrational energy corrections are included.

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General Perturb-Then-Diagonalize Model for the Vibrational Frequencies and Intensities of Molecules Belonging to Abelian and Non-Abelian Symmetry Groups

Cited by 25 publications

References 145 publications

Exploring Expansions of the Potential and Dipole Surfaces Used for Vibrational Perturbation Theory

Exploring Expansions of the Potential and Dipole Surfaces Used for Vibrational Perturbation Theory

An Effective and Automated Processing of Resonances in Vibrational Perturbation Theory Applied to Spectroscopy

Structural and Vibrational Properties of Amino Acids from Composite Schemes and Double-Hybrid DFT: Hydrogen Bonding in Serine as a Test Case

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