scholarly journals First-principles modeling of the infrared spectrum of antigorite

2021 ◽  
Vol 33 (4) ◽  
pp. 389-400
Author(s):  
Etienne Balan ◽  
Emmanuel Fritsch ◽  
Guillaume Radtke ◽  
Lorenzo Paulatto ◽  
Farid Juillot ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
New Caledonia ◽  
Infrared Absorption Spectrum ◽  
Single Mode ◽  
Asymmetric Distribution ◽  
Vibrational Modes ◽  
Density Functional Perturbation Theory ◽  
Composite Nature ◽  
Theory Framework

Abstract. The infrared absorption spectrum of a natural antigorite sample from New Caledonia is compared to its theoretical counterpart computed for the pristine antigorite m=17 polysome within the density functional perturbation theory framework. The theoretical model reproduces most of the bands related to Si-O stretching in the 800–1300 cm−1 range, OH libration, hindered OH translation and SiO4 bending in the 400–800 cm−1 range, and OH stretching in the 3500–3700 cm−1 range. Most of the observed bands have a composite nature involving several vibrational modes contributing to their intensity, except the apical and one of the basal Si-O stretching bands whose intensity is carried by a single mode. The peculiarity of the antigorite structure favors a localization of the Si-O and OH stretching modes in specific regions of the unit cell. Weaker Si-O stretching bands experimentally observed at 1205 and 1130 cm−1 are related to the occurrence of 6- and 8-reversals in the antigorite structure, respectively. The distribution of OH bond lengths leads to an asymmetric distribution of frequencies consistent with the width and the shape of the experimentally observed OH stretching band. It also leads to a strong distribution of OH libration frequencies ranging from 600 to 830 cm−1 explaining the asymmetry of the band observed at 648 cm−1 in the antigorite spectrum.

First-Principles Study of Structural and Vibrational Properties of α-SiO2 under Pressure

2015 ◽  
Vol 775 ◽  
pp. 191-196
Author(s):  
Xiao Wei Lei ◽  
Yong Song ◽  
Kuo Yang ◽  
Hui Zhao
Keyword(s):  
High Pressure ◽  
Perturbation Theory ◽  
Infrared Spectra ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Vibrational Properties ◽  
Vibrational Modes ◽  
Density Functional Perturbation Theory ◽  
Good Agreement

Using first principles approach, we present the structural, vibrational and dielectric properties of α-SiO2. The calculations have been carried out within the density functional perturbation theory and linear response formalism using the norm-concerving pseudopotentials and a plane wave basis. All the vibrational modes identified are in good agreement with experiment. The calculated infrared spectra are also in good agreement with available experimental results both for the positions and the intensities of the main peaks. We find that the modes Eu7 and A2u4 splits in two respectively at high hydrostaticpressures. Then we calculate the infrared spectra under high pressure of different orientations. The vibrational modes in different phase transitions are reported and discussed respectively.

scholarly journals Computational Modelling of Structural, Electronic, Optical and Vibrational Properties of PVK/C60 Nanoheterostructure Interfaces

2020 ◽  
Vol 11 (3) ◽  
pp. 10864-10884
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Computational Modelling ◽  
Phonon Modes ◽  
Functional Studies ◽  
Density Functional Perturbation Theory ◽  
Structural Differences ◽  
Dynamical Lattice ◽  
Quantum Espresso ◽  
Stacking Patterns

In this work, we present first-principles density functional studies of the dynamical properties of three nanoheterostructure interfaces of poly(9-vinylcarbazole)/fullerene (PVK/C60): PVK/C60(α), PVK/C60(β), and PVK/C60(γ). Linear response within density functional perturbation theory (DFPT), as implemented in the Quantum Espresso code, has been employed to explore the nature of permittivity, Born effective charges, polarizabilities, and vibrational frequency modes. The vibrational frequencies for the three nanoheterostructure interfaces were computed and their modes assigned. The phonon modes were also classified, and we showed that some important frequency modes are associated with C-C, CH2, and C−N stretching modes, among others. In addition, computed values of polarizability and permittivity for the nanoheterostructures were seen to have comparable values to that of literature for conjugated polymers. Conspicuous differing characteristics were noticed in the computed infrared and Raman absorption spectra for the three nanoheterostructures, which was due to the structural differences arising from their different stacking patterns. It is noted that the presence of the nitrogen atom plays a significant role in determining their dynamical lattice properties. The permittivity and polarizability tensors of PVK/C60(α), PVK/C60(β), and PVK/C60(γ) nanoheterostructures were found to be strongly anisotropic.

AB INITIO STUDY OF PHONON DISPERSION AND ELASTIC PROPERTIES OF L12 INTERMETALLICS Ti3Al AND Y3Al

2013 ◽  
Vol 27 (30) ◽  
pp. 1350224 ◽  
Author(s):  
N. ARIKAN ◽  
M. ERSEN ◽  
H. Y. OCAK ◽  
A. İYIGÖR ◽  
A. CANDAN ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Phonon Dispersion ◽  
High Symmetry ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Phonon Dispersion Curves ◽  
Lattice Constants ◽  
Density Functional Perturbation Theory ◽  
Phonon Properties

In this paper, the structural, elastic and phonon properties of Ti 3 Al and Y 3 Al in L1 2( Cu 3 Al ) phase are studied by performing first-principles calculations within the generalized gradient approximation. The calculated lattice constants, static bulk moduli, first-order pressure derivative of bulk moduli and elastic constants for both compounds are reported. The phonon dispersion curves along several high-symmetry lines at the Brillouin zone, together with the corresponding phonon density of states, are determined using the first-principles linear-response approach of the density functional perturbation theory. Temperature variations of specific heat in the range of 0–500 K are obtained using the quasi-harmonic model.

Remarkable improvement in phosgene detection with a defect-engineered phosphorene sensor: first-principles calculations

2020 ◽  
Vol 22 (17) ◽  
pp. 9677-9684 ◽  
Author(s):  
Mehdi Ghambarian ◽  
Zahra Azizi ◽  
Mohammad Ghashghaee
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Defect Engineering ◽  
Functional Theory ◽  
Remarkable Improvement ◽  
Black Phosphorene ◽  
First Time ◽  
Theory Framework

A drastic improvement in the phosgene sensitivity of black phosphorene with defect engineering is reported for the first time within a periodic density functional theory framework.

THEORETICAL INVESTIGATION OF THE ELASTIC PROPERTIES AND LATTICE DYNAMICS OF THE MgSxSe1-x ALLOY

2007 ◽  
Vol 21 (05) ◽  
pp. 249-259 ◽  
Author(s):  
K. BOUAMAMA ◽  
P. DJEMIA
Keyword(s):  
Elastic Properties ◽  
First Principles ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Local Density ◽  
Lattice Parameter ◽  
First Principles Calculations ◽  
Virtual Crystal Approximation ◽  
Functional Theory ◽  
Density Functional Perturbation Theory

Structural and elastic properties as well as lattice dynamics of ternary MgS x Se 1-x alloy have been studied using first-principles calculations. These are done using density functional theory (DFT) and density functional perturbation theory (DFPT) within the local density approximation (LDA) and employing the virtual-crystal approximation (VCA). We found that the lattice parameter, the elastic constants and the phonon frequencies follow a quadratic law in x.

Hydrogenation as a source of superconductivity in two-dimensional TiB2

2021 ◽  
pp. 2150057
Author(s):  
Hui Wang ◽  
Chen Pan ◽  
Sheng-Yan Wang ◽  
Hong Jiang ◽  
Yin-Chang Zhao ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Vibration Frequency ◽  
First Principles ◽  
Density Functional ◽  
Tensile Strain ◽  
2D Materials ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Density Functional Perturbation Theory ◽  
Potential Applications

Using first-principles calculations based on density functional perturbation theory, we demonstrate hydrogenation-induced superconductivity in monolayer TiB2H. Hydrogen adatoms destroy the Dirac state of monolayer TiB2 and monolayer TiB2H has a high vibration frequency. Monolayer TiB2H is a phonon-mediated superconductor. Monolayer TiB2H has a predicted [Formula: see text] of 8[Formula: see text]K, which further increases under external tensile strain. Thus, this study extends our understanding of superconductivity in two-dimensional (2D) materials and its potential applications.

First-principle studies of the lattice dynamics of crystals, and related properties

2005 ◽  
Vol 220 (5/6) ◽  
Author(s):  
Xavier Gonze ◽  
Gian-Marco Rignanese ◽  
Razvan Caracas
Keyword(s):  
Perturbation Theory ◽  
First Principles ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Computational Method ◽  
Dielectric Tensor ◽  
Atomic Temperature ◽  
Density Functional Perturbation Theory ◽  
Infra Red ◽  
Temperature Factors

AbstractThe crystal lattice is never rigid. Due to temperature, external fields or pressure, the nuclei vibrate, the lattice distorts, and instabilities can induce phase transitions. We review the basic concepts of density-functional perturbation theory, a computational method especially suited to determine from first-principles the microscopic parameters governing such behaviour. Then, we present the additional formalism leading to the following properties of minerals: the infra-red and Raman spectra; the prediction of (meta)stability or instability of a crystalline phase, based on the phonon spectrum; the computation of thermodynamics quantities like the free energy, entropy, specific heat; the atomic temperature factors. For each property, examples are given. When appropriate, we mention the computation of related properties, like dielectric tensor and Born effective charges that are needed to get infra-red spectra. Finally, we discuss briefly, on one hand, other applications of the density-functional perturbation theory, and, on the other hand, an alternative technique, the finite-difference computation of dynamical matrices.

Phonon Dispersions of a Single-Wall (8,0) Carbon Nanotube: Effects of the Rotational Acoustic Sum Rule and of Surface Attachment

2004 ◽  
Vol 858 ◽  
Author(s):  
Nicolas Mounet ◽  
Nicola Marzari
Keyword(s):  
Carbon Nanotubes ◽  
First Principles ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Single Walled Carbon Nanotubes ◽  
Vibrational Properties ◽  
Surface Attachment ◽  
Sum Rule ◽  
Density Functional Perturbation Theory ◽  
Walled Carbon Nanotubes

ABSTRACTThe lattice dynamics of single-walled carbon nanotubes (SWCNT) is studied from first-principles using density-functional perturbation theory (DFPT) at the GGA-PBE level. The phonon dispersions of a pristine, infinite zigzag (8,0) SWCNT are obtained and the effect of applying the rotational acoustic sum rule on vibrational properties is discussed. Finally we study the effects of covalent functionalizations on the SWCNT phonon frequencies by selectively increasing the effective mass of the carbon atoms that would link to the functional groups.

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