Vibrational Behavior of the −NO2 Group in Energetic Compounds

2005 ◽  
Vol 59 (10) ◽  
pp. 1194-1202 ◽  
Author(s):  
Royce W. Beal ◽  
Thomas B. Brill
Keyword(s):  
Density Functional ◽  
Plane Deformation ◽  
Nitroaromatic Compounds ◽  
Explosive Detection ◽  
Vibrational Modes ◽  
Internal Bonding ◽  
Energetic Compounds ◽  
Functional Theory ◽  
Out Of Plane ◽  
Plane Deformations

The vibrational modes of the –NO2 group in more than fifty energetic compounds containing the C-nitro and N-nitro functionalities were observed and then calculated in optimized structures using density functional theory (B3LYP/6–31+G*). The trends in the symmetric and asymmetric stretches and scissor and out-of-plane deformations were explained by these calculations. A previously unreported correlation was found between the nitro group internal bonding angle and its asymmetric stretching frequency. The concept of meta and ortho/para directing groups was applicable to the trends in coupled motions in the nitroaromatic compounds. Both the scissor motion of C–NO2 groups and the out-of-plane deformation of N–NO2 groups were found to be virtually insensitive to the remainder of the molecule. These findings may be useful in analytical methods of explosive detection based on their infrared (IR) spectra.

scholarly journals On the forbidden graphene’s ZO (out-of-plane optic) phononic band-analog vibrational modes in fullerenes

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Jesús N. Pedroza-Montero ◽  
Ignacio L. Garzón ◽  
Huziel E. Sauceda
Keyword(s):  
High Frequency ◽  
Density Functional ◽  
Room Temperature ◽  
Bulk Material ◽  
Characteristic Line ◽  
Vibrational Modes ◽  
Frequency Range ◽  
Functional Theory ◽  
Phonon Band ◽  
Out Of Plane

AbstractThe study of nanostructures’ vibrational properties is at the core of nanoscience research. They are known to represent a fingerprint of the system as well as to hint the underlying nature of chemical bonds. In this work, we focus on addressing how the vibrational density of states (VDOS) of the carbon fullerene family (Cn: n = 20 → 720 atoms) evolves from the molecular to the bulk material (graphene) behavior using density functional theory. We find that the fullerene’s VDOS smoothly converges to the graphene characteristic line-shape, with the only noticeable discrepancy in the frequency range of the out-of-plane optic (ZO) phonon band. From a comparison of both systems we obtain as main results that: (1) The pentagonal faces in the fullerenes impede the existence of the analog of the high frequency graphene’s ZO phonons, (2) which in the context of phonons could be interpreted as a compression (by 43%) of the ZO phonon band by decreasing its maximum allowed radial-optic vibration frequency. And 3) as a result, the deviation of fullerene’s VDOS relative to graphene may hold important thermodynamical implications, such as larger heat capacities compared to graphene at room-temperature. These results provide insights that can be extrapolated to other nanostructures containing pentagonal rings or pentagonal defects.

scholarly journals In-Process Measurement of Three-Dimensional Deformations Based on Speckle Photography

2021 ◽  
Vol 11 (11) ◽  
pp. 4981
Author(s):  
Andreas Tausendfreund ◽  
Dirk Stöbener ◽  
Andreas Fischer
Keyword(s):  
Evaluation Method ◽  
Process Analysis ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Machining Process ◽  
Image Correlation ◽  
Speckle Photography ◽  
Process Measurement ◽  
Out Of Plane ◽  
Plane Deformations

In the concept of the process signature, the relationship between a material load and the modification remaining in the workpiece is used to better understand and optimize manufacturing processes. The basic prerequisite for this is to be able to measure the loads occurring during the machining process in the form of mechanical deformations. Speckle photography is suitable for this in-process measurement task and is already used in a variety of ways for in-plane deformation measurements. The shortcoming of this fast and robust measurement technique based on image correlation techniques is that out-of-plane deformations in the direction of the measurement system cannot be detected and increases the measurement error of in-plane deformations. In this paper, we investigate a method that infers local out-of-plane motions of the workpiece surface from the decorrelation of speckle patterns and is thus able to reconstruct three-dimensional deformation fields. The implementation of the evaluation method enables a fast reconstruction of 3D deformation fields, so that the in-process capability remains given. First measurements in a deep rolling process show that dynamic deformations underneath the die can be captured and demonstrate the suitability of the speckle method for manufacturing process analysis.

Generating large out-of-plane piezoelectric properties of atomically thin MoS2 via the defect engineering

2021 ◽  
Author(s):  
Li-Ren Ng ◽  
Guan-Fu Chen ◽  
Shi-Hsin Lin
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Piezoelectric Properties ◽  
Two Dimensional ◽  
Defect Engineering ◽  
Functional Theory ◽  
Out Of Plane

We calculated the piezoelectric properties of asymmetrically defected MoS2 with density functional theory. By creating uneven numbers of defects on the either sides of two-dimensional MoS2, the out-of-plane centrosym- metry...

Tunable electronic properties of the dynamically stable layered mineral Pt2HgSe3 (Jacutingaite)

2020 ◽  
Vol 22 (42) ◽  
pp. 24471-24479 ◽  
Author(s):  
Asadollah Bafekry ◽  
Catherine Stampfl ◽  
Chuong Nguyen ◽  
Mitra Ghergherehchi ◽  
Bohayra Mortazavi
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
Electronic Properties ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Biaxial Strain ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Out Of Plane ◽  
Strain Layer

Density functional theory calculations are performed in order to study the structural and electronic properties of monolayer Pt2HgSe3. Effects of uniaxial and biaxial strain, layer thickness, electric field and out-of-plane pressure on the electronic properties are systematically investigated.

Identifying and explaining vibrational modes of quinacridones via temperature-resolved terahertz spectroscopy: absorption experiments and solid-state density functional theory simulations

2020 ◽  
Vol 22 (35) ◽  
pp. 19672-19679 ◽  
Author(s):  
A. D. Squires ◽  
Adam J. Zaczek ◽  
R. A. Lewis ◽  
Timothy M. Korter
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Density Functional ◽  
Terahertz Spectroscopy ◽  
State Density ◽  
Spectral Features ◽  
Thermal Contraction ◽  
Vibrational Modes ◽  
Functional Theory

New spectral features and anomalous shifting of vibrational modes of beta quinacridone are revealed, unusual thermal contraction the likely origin.

scholarly journals Structural, Electronic, and Vibrational Properties of Isoniazid and Its Derivative N-Cyclopentylidenepyridine-4-carbohydrazide: A Quantum Chemical Study

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Anoop kumar Pandey ◽  
Abhishek Bajpai ◽  
Vikas Baboo ◽  
Apoorva Dwivedi
Keyword(s):  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Basis Sets ◽  
Ground State Structure ◽  
Vibrational Modes ◽  
Functional Theory ◽  
Complete Assignment ◽  
Experimental Values ◽  
Homo Lumo

Isoniazid (Laniazid, Nydrazid), also known as isonicotinylhydrazine (INH), is an organic compound that is the first-line medication in prevention and treatment of tuberculosis. The optimized geometry of the isoniazid and its derivative N-cyclopentylidenepyridine-4-carbohydrazide molecule has been determined by the method of density functional theory (DFT). For both geometry and total energy, it has been combined with B3LYP functionals having LANL2DZ and 6-311 G (d, p) as the basis sets. Using this optimized structure, we have calculated the infrared wavenumbers and compared them with the experimental data. The calculated wavenumbers by LANL2DZ are in an excellent agreement with the experimental values. On the basis of fully optimized ground-state structure, TDDFT//B3LYP/LANL2DZ calculations have been used to determine the low-lying excited states of isoniazid and its derivative. Based on these results, we have discussed the correlation between the vibrational modes and the crystalline structure of isoniazid and its derivative. A complete assignment is provided for the observed FTIR spectra. The molecular HOMO, LUMO composition, their respective energy gaps, and MESP contours/surfaces have also been drawn to explain the activity of isoniazid and its derivative.

Electronic Structure, Nonlinear Optical Properties, and Vibrational Analysis of Ethyl benzoate by Density Functional Theory

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Tanveer Hasan ◽  
P. K. Singh
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Vibrational Analysis ◽  
Ethyl Benzoate ◽  
Computational Method ◽  
Basis Set ◽  
Vibrational Modes ◽  
Normal Coordinate ◽  
Functional Theory ◽  
Vibrational Bands

This work deals with the vibrational spectroscopy of Ethyl benzoate (C9H10O2). The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) using standard HF/6-31G(d,p) and B3LYP/6-31G(d,p) methods and basis set combinations. The vibrational spectra were interpreted, with the aid of normal coordinate analysis based on a scaled quantum mechanical force field. The infrared and Raman spectra were also predicted from the calculated intensities. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes.

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