Evaluation of Molecular Polarizability and of Intensity Carrying Modes Contributions in Circular Dichroism Spectroscopies

Zanchi, Chiara; Longhi, Giovanna; Abbate, Sergio; Pellegrini, Giovanni; Biagioni, Paolo; Tommasini, Matteo

doi:10.3390/app9214691

Cited by 5 publications

(9 citation statements)

References 88 publications

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“…In the Appendix 1, it is shown that for a given applied field F , the equilibrium positions of the atoms in the molecule change along each normal coordinate according to The combination of eqs and leads to the first-order field-dependence of the dipole that includes the effects of molecular structure relaxation through the so-called vibrational polarizability α r ( 0 , 0 ) The expression of vibrational polarizability α r given by eq matches those obtained by different approaches in the past (see for instance refs − ). Clearly, based on eq , when applying an electric field F , the molecular dipole changes according to an effective polarizability, which is given by the sum of the electronic polarizability α e ( 0 , 0 ) (clamped nuclei) and the vibrational polarizability α r ( 0 , 0 ) that accounts for the relaxation of the molecular structure.…”

Section: Theoretical Frameworkmentioning

confidence: 67%

Electric-Field-Induced Effects on the Dipole Moment and Vibrational Modes of the Centrosymmetric Indigo Molecule

et al. 2020

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Intense static electric fields can strongly perturb chemical bonds and induce frequency shifts of the molecular vibrations in the so-called vibrational Stark effect. Based on a density functional theory (DFT) approach, here, we report a detailed investigation of the influence of oriented external electric fields (OEEFs) on the dipole moment and infrared (IR) spectrum of the nonpolar centrosymmetric indigo molecule. When an OEEF as intense as ∼0.1 V Å–1 is applied, several modifications in the IR spectrum are observed. Besides the notable frequency shift of some modes, we observe the onset of new bandsforbidden by the selection rules in the zero-field case. Such a neat field-induced modification of the vibrational selection rules, and the subsequent variations of the peaks’ intensities in the IR spectrum, paves the way toward the design of smart tools employing centrosymmetric molecules as proxies for mapping local electric fields. In fact, here, we show that the ratio between the IR and the Raman intensities of selected modes is proportional to the square of the local field. This indicator can be used to quantitatively measure local fields, not only in condensed matter systems under standard conditions but also in field-emitting-tip apparatus.

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Section: Theoretical Frameworkmentioning

confidence: 67%

Electric-Field-Induced Effects on the Dipole Moment and Vibrational Modes of the Centrosymmetric Indigo Molecule

et al. 2020

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“…Furthermore, since its publication in 2018, 17 separate projects to date have leveraged the Psi4NumPy framework to facilitate their development of novel quantum chemical methods. [101][102][103][104][105][106][107][108][109][110][111][112][113][114][115][116][117] Finally, Psi4NumPy is a thoroughly community-driven project; interested readers are highly encouraged to visit the repository 100 for the latest version of Psi4NumPy and to participate in "pull request" code review, issue tracking, or by contributing code to the project itself.…”

Section: A Psi4numpymentioning

confidence: 99%

PSI4 1.4: Open-source software for high-throughput quantum chemistry

Smith

Burns

Simmonett

et al. 2020

The Journal of Chemical Physics

620

477

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Psi4 is a free and open-source ab initio electronic structure program providing Hartree-Fock, density functional theory, many-body perturbation theory, configuration interaction, density cumulant theory, symmetry-adapted perturbation theory, and coupled-cluster theory. Most of the methods are quite efficient thanks to density fitting and multi-core parallelism. The program is a hybrid of C++ and Python, and calculations may be run with very simple text files or using the Python API, facilitating post-processing and complex workflows; method developers also have access to most of Psi4's core functionality via Python. Job specification may be passed using The Molecular Sciences Software Institute (MolSSI) QCSchema data format, facilitating interoperability. A rewrite of our top-level computation driver, and concomitant adoption of the MolSSI QCArchive Infrastructure project, make the latest version of Psi4 well suited to distributed computation of large numbers of independent tasks. The project has fostered the development of independent software components that may be reused in other quantum chemistry programs. File list (2) download file view on ChemRxiv psi4.pdf (4.37 MiB) download file view on ChemRxiv supplementary_material.pdf (297.86 KiB)

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“…The static spectrum of the gas-phase isolated 1S-FEN molecule discussed in the next section was computed with the Gaussian16 code, VCD package, , in the double harmonic approximation. Previous works have shown that the B3LYP functional , with the aug-cc-TZvp bais set , allows for correctly reproducing all the main features of the experimental spectrum in the fingerprint region. Therefore, the same computational setup was adopted here.…”

Section: Benchmarkmentioning

confidence: 99%

“…Due to the variety and complexity of the factors interplaying in determining the spectral shape, the interpretation of spectroscopic data based on experimental measurements alone can lead to uncertainties and ambiguities. In this respect, theoretical calculations are a powerful tool for analyzing the connection between structure and spectroscopic marker bands. − …”

Section: Introductionmentioning

confidence: 99%

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Vibrational Circular Dichroism from DFT Molecular Dynamics: The AWV Method

Galimberti¹

2022

J. Chem. Theory Comput.

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The paper illustrates the Activity Weighted Velocities (AWV) methodology to compute Vibrational Circular Dichroism (VCD) anharmonic spectra from Density Functional Theory (DFT) molecular dynamics. AWV calculates the spectra by the Fourier Transform of the time correlation functions of velocities, weighted by specific observables: the Atomic Polar Tensors (APTs) and the Atomic Axial Tensors (AATs). Indeed, AWV shows to correctly reproduce the experimental spectra for systems in the gas and liquid phases, both in the case of weakly and strongly interacting systems. The comparison with the experimental spectra is striking especially in the fingerprint region, as demonstrated by the three benchmark systems discussed: (1S)-Fenchone in the gas phase, (S)-(−)-Propylene oxide in the liquid phase, and (R)-(−)-2-butanol in the liquid phase. The time evolution of APTs and AATs can be adequately described by a linear combination of the tensors of a small set of appropriate reference structures, strongly reducing the computational cost without compromising accuracy. Additionally, AWV allows the partition of the spectral signal in its molecular components without any expensive postprocessing and any localization of the charge density or the wave function.

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Evaluation of Molecular Polarizability and of Intensity Carrying Modes Contributions in Circular Dichroism Spectroscopies

Cited by 5 publications

References 88 publications

Electric-Field-Induced Effects on the Dipole Moment and Vibrational Modes of the Centrosymmetric Indigo Molecule

Electric-Field-Induced Effects on the Dipole Moment and Vibrational Modes of the Centrosymmetric Indigo Molecule

PSI4 1.4: Open-source software for high-throughput quantum chemistry

Vibrational Circular Dichroism from DFT Molecular Dynamics: The AWV Method

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