scholarly journals Symmetry/Asymmetry of the NHN Hydrogen Bond in Protonated 1,8-Bis(dimethylamino)naphthalene

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1924
Author(s):  
Patrycja Piękoś ◽  
Aneta Jezierska ◽  
Jarosław J. Panek ◽  
Eugene A. Goremychkin ◽  
Alexander F. Pozharskii ◽  
...  
Keyword(s):  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Functional Theory ◽  
Protonated Forms ◽  
Motional Dynamics ◽  
Proton Dynamics ◽  
Experimental Findings ◽  
Bridge Vibrations ◽  
Theoretical Results

Experimental and theoretical results are presented based on vibrational spectra and motional dynamics of 1,8-bis(dimethylamino)naphthalene (DMAN) and its protonated forms (DMANH+ and the DMANH+ HSO4− complex). The studies of these compounds have been performed in the gas phase and solid-state. Spectroscopic investigations were carried out by infrared spectroscopy (IR), Raman, and incoherent inelastic neutron scattering (IINS) experimental methods. Density functional theory (DFT) and Car–Parrinello molecular dynamics (CPMD) methods were applied to support our experimental findings. The fundamental investigations of hydrogen bridge vibrations were accomplished on the basis of isotopic substitutions (NH → ND). Special attention was paid to the bridged proton dynamics in the DMANH+ complex, which was found to be affected by interactions with the HSO4− anion.

scholarly journals Study of Anharmonicity in Zirconium Hydrides Using Inelastic Neutron Scattering and Ab-Initio Computer Modeling

Inorganics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 29
Author(s):  
Jiayong Zhang ◽  
Yongqiang Cheng ◽  
Alexander I. Kolesnikov ◽  
Jerry Bernholc ◽  
Wenchang Lu ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Excited States ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Vibrational States ◽  
Functional Theory ◽  
Hydrogen Deuterium ◽  
Zirconium Hydrides

The anharmonic phonon behavior in zirconium hydrides and deuterides, including ϵ-ZrH2, γ-ZrH, and γ-ZrD, has been investigated from aspects of inelastic neutron scattering (INS) and lattice dynamics calculations within the framework of density functional theory (DFT). The harmonic model failed to reproduce the spectral features observed in the experimental data, indicating the existence of anharmonicity in those materials and the necessity of further explanations. Here, we present a detailed study on the anharmonicity in zirconium hydrides/deuterides by exploring the 2D potential energy surface of hydrogen/deuterium atoms and solving the corresponding 2D single-particle Schrödinger equation to obtain the eigenfrequencies, which are then convoluted with the instrument resolution. The convoluted INS spectra qualitatively describe the anharmonic peaks in the experimental INS spectra and demonstrate that the anharmonicity originates from the deviations of hydrogen potentials from quadratic behavior in certain directions; the effects are apparent for the higher-order excited vibrational states, but small for the ground and first excited states.

scholarly journals DFT Simulations of the Vibrational Spectrum and Hydrogen Bonds of Ice XIV

Molecules ◽  
2018 ◽  
Vol 23 (7) ◽  
pp. 1781 ◽  
Author(s):  
Kai Zhang ◽  
Peng Zhang ◽  
Ze-Ren Wang ◽  
Xu-Liang Zhu ◽  
Ying-Bo Lu ◽  
...  
Keyword(s):  
Vibrational Spectrum ◽  
Normal Vibration ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
General Rule ◽  
Experimental Spectrum ◽  
Inelastic Neutron ◽  
Functional Theory ◽  
Ir And Raman ◽  
Normal Vibration Frequencies

It is always a difficult task to assign the peaks recorded from a vibrational spectrum. Herein, we explored a new pathway of density functional theory (DFT) simulation to present three kinds of spectra of ice XIV that can be referenced as inelastic neutron scattering (INS), infrared (IR), and Raman experimental spectrum. The INS spectrum is proportional to the phonon density of states (PDOS) while the photon scattering signals reflect the normal vibration frequencies near the Brillouin zone (BZ) center. Based on good agreements with the experimental data, we identified the relative frequency and made scientific assignments through normal vibration modes analysis. The two hydrogen bond (H-bond) peaks among the ice phases from INS were discussed and the dynamic process of the H-bond vibrations was found to be classified into two basic modes. We deduced that two H-bond modes are a general rule among the ice family and more studies are ongoing to investigate this subject.

scholarly journals Vibrational Dynamics of Crystalline 4-Phenylbenzaldehyde from INS Spectra and Periodic DFT Calculations

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1374
Author(s):  
Mariela M. Nolasco ◽  
Catarina F. Araujo ◽  
Pedro D. Vaz ◽  
Ana M. Amado ◽  
Paulo Ribeiro-Claro
Keyword(s):  
Dft Calculations ◽  
Single Molecule ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Torsional Mode ◽  
Functional Theory ◽  
Periodic Dft Calculations ◽  
Periodic Calculations ◽  
Unambiguous Assignment

The present work emphasizes the value of periodic density functional theory (DFT) calculations in the assessment of the vibrational spectra of molecular crystals. Periodic calculations provide a nearly one-to-one match between the calculated and observed bands in the inelastic neutron scattering (INS) spectrum of crystalline 4-phenylbenzaldehyde, thus validating their assignment and correcting previous reports based on single molecule calculations. The calculations allow the unambiguous assignment of the phenyl torsional mode at ca. 118–128 cm−1, from which a phenyl torsional barrier of ca. 4000 cm−1 is derived, and the identification of the collective mode involving the antitranslational motion of CH···O bonded pairs, a hallmark vibrational mode of systems where C-H···O contacts are an important feature.

scholarly journals On the microscopic dynamics of the ‘Einstein solids’ AlV2Al20 and GaV2Al20, and of YV2Al20: a benchmark system for ‘rattling’ excitations

2015 ◽  
Vol 17 (38) ◽  
pp. 24837-24850 ◽  
Author(s):  
Michael Marek Koza ◽  
Hannu Mutka ◽  
Yoshihiko Okamoto ◽  
Jun-ichi Yamaura ◽  
Zenji Hiroi
Keyword(s):  
Density Functional Theory ◽  
High Resolution ◽  
Neutron Scattering ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Functional Theory ◽  
Inelastic Response ◽  
Benchmark System

The inelastic response of AV2Al20 (with A = Al, Ga and Y) was probed by high-resolution inelastic neutron scattering experiments and density functional theory (DFT) based lattice dynamics calculations (LDC).

scholarly journals Solid wetting-layers in inorganic nano-reactors: the water in imogolite nanotube case

2020 ◽  
Vol 2 (5) ◽  
pp. 1869-1877 ◽  
Author(s):  
Geoffrey Monet ◽  
Erwan Paineau ◽  
Ziwei Chai ◽  
Mohamed S. Amara ◽  
Andrea Orecchini ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Neutron Scattering ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Original Structure ◽  
Functional Theory ◽  
Inner Surface ◽  
Wetting Layers

The discovery of an original structure of the water at the inner surface of inorganic aluminogermanate nanotubes and its specific dynamics are reported, based on density functional theory molecular dynamics and inelastic neutron scattering.

scholarly journals Vibrational spectroscopy of metal methanesulfonates: M = Na, Cs, Cu, Ag, Cd

2018 ◽  
Vol 5 (4) ◽  
pp. 171574 ◽  
Author(s):  
Stewart F. Parker ◽  
Lisha Zhong
Keyword(s):  
Density Functional Theory ◽  
Vibrational Spectroscopy ◽  
Spectroscopic Data ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Functional Theory ◽  
Methyl Group ◽  
Transition Energies ◽  
Mode Of Coordination

In this work, we have used a combination of vibrational spectroscopy (infrared, Raman and inelastic neutron scattering) and periodic density functional theory to investigate six metal methanesulfonate compounds that exhibit four different modes of complexation of the methanesulfonate ion: ionic, monodentate, bidentate and pentadentate. We found that the transition energies of the modes associated with the methyl group (C–H stretches and deformations, methyl rock and torsion) are essentially independent of the mode of coordination. The SO 3 modes in the Raman spectra also show little variation. In the infrared spectra, there is a clear distinction between ionic (i.e. not coordinated) and coordinated forms of the methanesulfonate ion. This is manifested as a splitting of the asymmetric S–O stretch modes of the SO 3 moiety. Unfortunately, no further differentiation between the various modes of coordination: unidentate, bidentate etc … is possible with the compounds examined. While it is likely that such a distinction could be made, this will require a much larger dataset of compounds for which both structural and spectroscopic data are available than that available here.

scholarly journals Understanding the Structure and Dynamics of Nanocellulose-Based Composites with Neutral and Ionic Poly(methacrylate) Derivatives Using Inelastic Neutron Scattering and DFT Calculations

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1689
Author(s):  
Carla Vilela ◽  
Carmen S. R. Freire ◽  
Catarina Araújo ◽  
Svemir Rudić ◽  
Armando J. D. Silvestre ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Density Functional Theory Calculations ◽  
Inelastic Neutron ◽  
Spectral Lines ◽  
Model Systems ◽  
Functional Theory ◽  
Bacterial Nanocellulose ◽  
Structure And Dynamics

Bacterial nanocellulose (BC)-based composites containing poly(2-hydroxyethyl methacrylate) (PHEMA), poly(methacroylcholine chloride) (PMACC) or poly(methacroylcholine hydroxide) (PMACH) were characterized by inelastic neutron scattering (INS) spectroscopy, combined with DFT (density functional theory) calculations of model systems. A reasonable match between calculated and experimental spectral lines and their intensities was used to support the vibrational assignment of the observed bands and to validate the possible structures. The differences between the spectra of the nanocomposites and the pure precursors indicate that interactions between the components are stronger for the ionic poly(methacrylate) derivatives than for the neutral counterpart. Displaced anions interact differently with cellulose chains, due to the different ability to compete with the O–H···O hydrogen bonds in cellulose. Hence, the INS is an adequate technique to delve deeper into the structure and dynamics of nanocellulose-based composites, confirming that they are true nanocomposite materials instead of simple mixtures of totally independent domains.

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