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Artykuły w czasopismach na temat „Lattice Vibrational Modes”

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Data publikacji: 6 września 2023

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1

Prabhu, V. V., W. K. Schroll, L. L. Van Zandt, and E. W. Prohofsky. "Helical lattice vibrational modes in DNA." Physical Review Letters 60, no. 15 (1988): 1587. http://dx.doi.org/10.1103/physrevlett.60.1587.

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2

Kuimov, I. M., I. O. Raikov, and D. A. Parshin. "Vibrational dynamics in 2D crystal lattices of borophene." Journal of Physics: Conference Series 2086, no. 1 (2021): 012021. http://dx.doi.org/10.1088/1742-6596/2086/1/012021.

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Abstract Vibration dynamics of crystalline borophene is considered in the framework of the Born–von Karman model. The vibrations perpendicular to the plane of 2D borophen lattice (flexural modes) are studied.

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3

Iftikhar, Aneeza, A. Afaq, Iftikhar Ahmad, et al. "Computational Study of Ru2TiZ (Z = Si, Ge, Sn) for Structural, Mechanical and Vibrational Properties." Zeitschrift für Naturforschung A 74, no. 6 (2019): 545–50. http://dx.doi.org/10.1515/zna-2019-0054.

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AbstractThe structural, mechanical and vibrational properties of Ru2TiZ (Z = Si, Ge, Sn) Full Heusler Alloys (FHAs) are computed using PBE-GGA as an exchange-correlation functional in Kohn–Sham equations. The calculated lattice constants of these alloys in L21 phase deviate from experimental values upto 0.85 % which shows a good agreement between the model and the experiments. These lattice constants are then used to compute the second order elastic constants C11, C12 and C44 with Wien2k-code. Elastic moduli and mechanical parameters are also calculated by these three independent elastic constants. Mechanical parameters Pugh’s and Poisson’s ratio indicate non-brittle nature of these alloys. Furthermore, the Debye temperature where the collective vibrations shift to an independent thermal vibration, longitudinal and transverse sound velocities, melting temperatures, and thermal conductivities are also obtained to investigate the phonon modes of oscillation. These phonon modes confirm the stability of these alloys as there exists no imaginary phonon frequency in the phonon-dispersion curves.

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4

Bachurina, Olga V., Ramil T. Murzaev, and Dmitry V. Bachurin. "Molecular dynamics study of two-dimensional discrete breather in nickel." Journal of Micromechanics and Molecular Physics 04, no. 02 (2019): 1950001. http://dx.doi.org/10.1142/s2424913019500012.

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A discrete breather (DB) is a spatially localized vibrational mode of large amplitude in a defect-free anharmonic lattice. Generally, zero-dimensional DB is considered to be localized in all [Formula: see text] directions of the [Formula: see text]-dimensional lattice. However, the question of existence of DBs localized in [Formula: see text]–[Formula: see text] directions and delocalized in other [Formula: see text] directions remains open. In the present paper, for the first time, the case of [Formula: see text] and [Formula: see text] is considered by constructing a two-dimensional (2D) DB in the fcc nickel lattice using molecular dynamics methods. In order to excite such DB, one of the delocalized vibrational modes of the triangular lattice was used (the (111) plane in fcc crystal is a triangular lattice). All simulations were carried out at zero temperature. The investigated 2D DB demonstrates hard-type nonlinearity, when its oscillation frequency increases with increasing amplitude. The oscillation frequencies of the DB are above the upper edge of the phonon spectrum for nickel, which is 10.3[Formula: see text]THz. The maximum DB lifetime is found to be 9.5[Formula: see text]ps. The obtained results expand our understanding of diversity of nonlinear spatially localized vibrational modes in nonlinear lattices.

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5

Tomaschitz, Roman. "Thermodynamics of lattice vibrations in non-cubic crystals: the zinc structure revisited." Acta Crystallographica Section A Foundations and Advances 77, no. 5 (2021): 420–32. http://dx.doi.org/10.1107/s2053273321005507.

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A phenomenological model of anisotropic lattice vibrations is proposed, using a temperature-dependent spectral cutoff and varying Debye temperatures for the vibrational normal components. The internal lattice energy, entropy and Debye–Waller B factors of non-cubic elemental crystals are derived. The formalism developed is non-perturbative, based on temperature-dependent linear dispersion relations for the normal modes. The Debye temperatures of the vibrational normal components differ in anisotropic crystals; their temperature dependence and the varying spectral cutoff can be inferred from the experimental lattice heat capacity and B factors by least-squares regression. The zero-point internal energy of the phonons is related to the low-temperature limits of the mean-squared vibrational amplitudes of the lattice measured by X-ray and γ-ray diffraction. A specific example is discussed, the thermodynamic variables of the hexagonal close-packed zinc structure, including the temperature evolution of the B factors of zinc. In this case, the lattice vibrations are partitioned into axial and basal normal components, which admit largely differing B factors and Debye temperatures. The second-order B factors defining the non-Gaussian contribution to the Debye–Waller damping factors of zinc are obtained as well. Anharmonicity of the oscillator potential and deviations from the uniform phonon frequency distribution of the Debye theory are modeled effectively by the temperature dependence of the spectral cutoff and Debye temperatures.

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6

Smith, PW, and R. Stranger. "Vibrational-Spectra of Salts of the Type-AI3[Mo2X9] with X = Cl, Br, I." Australian Journal of Chemistry 39, no. 8 (1986): 1269. http://dx.doi.org/10.1071/ch9861269.

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The far-infrared and Raman spectra of a series of alkali, ammonium and alkylammonium salts of Mo2X93- (X = Cl , Br, I) have been measured. All observed infrared-active vibrations, including lattice modes, together with certain Raman-active modes, have been assigned for the alkali salts of Mo2Cl93- on the basis of the D6h unit cell symmetry which applies. The vibrational assignments for the corresponding bromide and iodide complexes follow in the same relative order as those of Mo2Cl93-. The splitting of degenerate modes for certain alkylammonium salts of Mo2Cl93- has been interpreted on the basis of C2v symmetry applicable to these particular salts. By correlating the spectral changes observed with variation of the cation, it has been possible to distinguish the bridging-halogen deformation modes from neighbouring lattice modes.

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7

Chechin, George, Denis Ryabov, and Stepan Shcherbinin. "Large-amplitude periodic atomic vibrations in diamond." Journal of Micromechanics and Molecular Physics 03, no. 01n02 (2018): 1850002. http://dx.doi.org/10.1142/s2424913018500029.

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Symmetry-determined nonlinear normal modes, which describe large-amplitude vibrations of diamond lattice, are studied by specific group-theoretical methods. For two of these modes, corresponding to vibrational state with and without multiplication of the unit cell, we present their atomic patterns and dynamical properties obtained with the aid of the ab initio simulations based on the density functional theory (DFT).

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8

Radionov, M. S., S. A. Klimin, A. Yu Glamazda, and A. V. Peschanskii. "IR vibrational modes and spin-phonon interplay in magnetoelectric LiNiPO₄." Low Temperature Physics 48, no. 3 (2022): 246–52. http://dx.doi.org/10.1063/10.0009544.

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LiNiPO4, multifunctional material with potential ionic current and magnetoelectric applications, was studied by IR optical spectroscopy and lattice dynamic shell-model calculations. We present IR phonon parameters of lithium-nickel-phosphate, both experimental (at T = 30 K) and calculated ones. Multiferroic properties of lithium-nickel-phosphate were confirmed by temperature evolution of phonon band parameters due to spin-phonon interaction revealed for a number of phonon modes. The most pronounced effect was registered for B2 u IR-vibrational mode near 202 cm−1, which demonstrates anomalous temperature behavior in the vicinity of magnetic ordering ( TN = 21.8 K) indicating the coupling to the magnetic subsystem. This mode is assigned to the complex normal vibration including the librations of the PO4 tetrahedra, out-of-plane vibrations of the Li atoms, and the in-plane vibrations of the magnetic Ni atoms along the b axis. The detected phonon shift at TN can be explained by the striction phenomena.

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9

Щербинин, С. А., М. Н. Семенова, А. С. Семенов, Е. А. Корзникова, Г. М. Чечин та С. В. Дмитриев. "Динамика трехкомпонентной делокализованной нелинейной колебательной моды в графене". Физика твердого тела 61, № 11 (2019): 2163. http://dx.doi.org/10.21883/ftt.2019.11.48423.444.

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AbstractThe dynamics of a three-component nonlinear delocalized vibrational mode in graphene is studied with molecular dynamics. This mode, being a superposition of a root and two one-component modes, is an exact and symmetrically determined solution of nonlinear equations of motion of carbon atoms. The dependences of a frequency, energy per atom, and average stresses over a period that appeared in graphene are calculated as a function of amplitude of a root mode. We showed that the vibrations become periodic with certain amplitudes of three component modes, and the vibrations of one-component modes are close to periodic one and have a frequency twice the frequency of a root mode, which is noticeably higher than the upper boundary of a spectrum of low-amplitude vibrations of a graphene lattice. The data obtained expand our understanding of nonlinear vibrations of graphene lattice.

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10

TALATI, MINA, and PRAFULLA K. JHA. "TEMPERATURE EFFECT ON VIBRATIONAL PROPERTIES OF La0.7Sr0.3MnO3." International Journal of Modern Physics B 23, no. 23 (2009): 4767–77. http://dx.doi.org/10.1142/s0217979209053783.

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Temperature dependence of phonons spectra and allied properties of rhombohedral La 0.7 Sr 0.3 MnO 3 are investigated by using the lattice dynamical method. A tendency of phonon mode to instability causing JT lattice distortion is reflected in a softening of the stretching mode in the phonon dispersion curve of La 0.7 Sr 0.3 MnO 3 at both 1.6 and 300 K. While the A1g mode softens because of gradual decrease in MnO 6 rotations, the stretching mode hardens upon reduction in temperature. The distinct features of phonon modes at different temperatures are also reflected in the calculated phonon density of states. Other thermal properties such as specific heat, the Debye temperature, and Grüneisen parameter are also presented. The decrease in the Debye temperature at 300 K indicates the effect of temperature in lattice softening. Anomalously high value of the Grüneisen parameter points out the presence of anharmonic lattice modes.

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11

Cousineau, Émilie, Samik Mukherjee, Assali Simone, Jérôme Nicolas, and Oussama Moutanabbir. "Lattice Vibrational Modes in Epitaxial Metastable Germanium-Tin Semiconductors." ECS Meeting Abstracts MA2020-01, no. 22 (2020): 1320. http://dx.doi.org/10.1149/ma2020-01221320mtgabs.

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12

de Moura, F. A. B. F. "Vibrational modes in a two-dimensional aperiodic harmonic lattice." Journal of Physics: Condensed Matter 22, no. 43 (2010): 435401. http://dx.doi.org/10.1088/0953-8984/22/43/435401.

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13

Rez, Peter, and Arunima Singh. "Lattice resolution of vibrational modes in the electron microscope." Ultramicroscopy 220 (January 2021): 113162. http://dx.doi.org/10.1016/j.ultramic.2020.113162.

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14

Srivastava, Umesh Chandra, and Shyamendra Pratap Singh. "Structural and Vibrational Properties of Solid Naphthalene (C10H8) by Use of VTBFS Model." Oriental Journal Of Chemistry 38, no. 3 (2022): 762–65. http://dx.doi.org/10.13005/ojc/380329.

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In this article author’s are reporting lattice dynamical properties of naphthalene (C10H8) by use of VTBFS model. we also report the combined density of states (CDS), dispersion relation and elastic properties of naphthalene. So, use of the present model the lattice property of naphthalene is reported successfully. Moreover, within our reported result the lattice modes exhibit more drastic changes in the structural and vibrational properties of naphthalene.

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15

Serra-Garcia, Marc, Miguel Molerón, and Chiara Daraio. "Tunable, synchronized frequency down-conversion in magnetic lattices with defects." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, no. 2127 (2018): 20170137. http://dx.doi.org/10.1098/rsta.2017.0137.

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We study frequency conversion in nonlinear mechanical lattices, focusing on a chain of magnets as a model system. We show that, by inserting mass defects at suitable locations, we can introduce localized vibrational modes that nonlinearly couple to extended lattice modes. The nonlinear interaction introduces an energy transfer from the high-frequency localized modes to a low-frequency extended mode. This system is capable of autonomously converting energy between highly tunable input and output frequencies, which need not be related by integer harmonic or subharmonic ratios. It is also capable of obtaining energy from multiple sources at different frequencies with a tunable output phase, due to the defect synchronization provided by the extended mode. Our lattice is a purely mechanical analogue of an opto-mechanical system, where the localized modes play the role of the electromagnetic field and the extended mode plays the role of the mechanical degree of freedom. This article is part of the theme issue ‘Nonlinear energy transfer in dynamical and acoustical systems’.

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16

Quan, Li Na, Yoonjae Park, Peijun Guo, et al. "Vibrational relaxation dynamics in layered perovskite quantum wells." Proceedings of the National Academy of Sciences 118, no. 25 (2021): e2104425118. http://dx.doi.org/10.1073/pnas.2104425118.

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Organic–inorganic layered perovskites, or Ruddlesden–Popper perovskites, are two-dimensional quantum wells with layers of lead-halide octahedra stacked between organic ligand barriers. The combination of their dielectric confinement and ionic sublattice results in excitonic excitations with substantial binding energies that are strongly coupled to the surrounding soft, polar lattice. However, the ligand environment in layered perovskites can significantly alter their optical properties due to the complex dynamic disorder of the soft perovskite lattice. Here, we infer dynamic disorder through phonon dephasing lifetimes initiated by resonant impulsive stimulated Raman photoexcitation followed by transient absorption probing for a variety of ligand substitutions. We demonstrate that vibrational relaxation in layered perovskite formed from flexible alkyl-amines as organic barriers is fast and relatively independent of the lattice temperature. Relaxation in layered perovskites spaced by aromatic amines is slower, although still fast relative to bulk inorganic lead bromide lattices, with a rate that is temperature dependent. Using molecular dynamics simulations, we explain the fast rates of relaxation by quantifying the large anharmonic coupling of the optical modes with the ligand layers and rationalize the temperature independence due to their amorphous packing. This work provides a molecular and time-domain depiction of the relaxation of nascent optical excitations and opens opportunities to understand how they couple to the complex layered perovskite lattice, elucidating design principles for optoelectronic devices.

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17

Wang, Ze-Ren, Xu-Liang Zhu, Lu Jiang, et al. "Investigations of the Hydrogen Bonds and Vibrational Spectra of Clathrate Ice XVI." Materials 12, no. 2 (2019): 246. http://dx.doi.org/10.3390/ma12020246.

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Natural gas hydrates are ice-like crystalline materials formed from natural gas and clathrate ice under high pressure and low temperature. Ice XVI, the first S-II type clathrate ice produced in the lab, was simulated by first-principles density functional theory with the CASTEP code. A 34-molecule supercell was built to mimic the hydrogen-disordered structure. The vibrational spectra were calculated as a reference for inelastic neutron scattering (INS), infrared (IR) absorption, and Raman scattering experiments. Two kinds of H-bond vibration modes corresponding to two different bond strengths were found in our previous studies. In this paper, the statistics of distribution calculated by integrating these two kinds of modes was found to match the phonon density of states (PDOS) very well. We confirmed that the two basic types of H-bonds also appeared in clathrate ice XVI. The typical normal modes were analyzed to illustrate the dynamic process of lattice vibrations.

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18

Kaschner, A., H. Siegle, A. Hoffmann, et al. "Influence of Doping on the Lattice Dynamics of Gallium Nitride." MRS Internet Journal of Nitride Semiconductor Research 4, S1 (1999): 327–32. http://dx.doi.org/10.1557/s1092578300002672.

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We present results of Raman-scattering experiments on GaN doped with Si, C, and Mg, respectively, grown by molecular beam epitaxy (MBE). The influence of the different dopants on strain and free-carrier concentration was investigated. Furthermore, we report on several local vibrational modes (LVM) around 2200 cm−1 in Raman spectra of highly Mg-doped GaN. A possible explanation of these high-energy modes in terms of hydrogen-related vibrations is given. We also found a variety of new structures in the range of the GaN host lattice phonons. Secondary ion mass spectroscopy (SIMS) was applied to determine the concentration of magnesium and unintentionally incorporated hydrogen.

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19

Chen, C. S., and D. K. Schroder. "Lattice distortions and vibrational modes of substitutional impurities in silicon." Physical Review B 35, no. 2 (1987): 713–17. http://dx.doi.org/10.1103/physrevb.35.713.

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20

Zhernov, A. P., and E. P. Chulkin. "Localization of acoustic vibrational modes in a chain-type lattice." Journal of Experimental and Theoretical Physics 90, no. 2 (2000): 308–18. http://dx.doi.org/10.1134/1.559105.

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21

Fei, Ruixiang, and Li Yang. "Lattice vibrational modes and Raman scattering spectra of strained phosphorene." Applied Physics Letters 105, no. 8 (2014): 083120. http://dx.doi.org/10.1063/1.4894273.

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22

Yang, Li, and M. Y. Chou. "Lattice Vibrational Modes and their Frequency Shifts in Semiconductor Nanowires." Nano Letters 11, no. 7 (2011): 2618–21. http://dx.doi.org/10.1021/nl200523f.

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23

Emelie, P. Y., J. D. Phillips, B. Buller, and U. D. Venkateswaran. "Free carrier absorption and lattice vibrational modes in bulk ZnO." Journal of Electronic Materials 35, no. 4 (2006): 525–29. http://dx.doi.org/10.1007/s11664-006-0094-0.

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24

Джахангирли, З. А., Р. Г. Велиев, И. А. Мамедова та ін. "Ab initio и экспериментальное исследование колебательных свойств кристаллов TlFeS-=SUB=-2-=/SUB=- и TlFeSe-=SUB=-2-=/SUB=-". Физика твердого тела 63, № 10 (2021): 1637. http://dx.doi.org/10.21883/ftt.2021.10.51416.099.

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The lattice vibrational properties of TlFeS2 and TlFeSe2 crystals have been studied experimentally using Raman scattering (RS) and infrared reflection (IR) light, as well as theoretically using density functional theory (DFT). The complete vibrational representation, based on the analysis of the factor site symmetry, contains 12 active Raman modes and 9 IR active modes. 6 RS active and 3 IR active modes of them for TlFeS2, and 4 RS active and 3 IR active modes for TlFeSe2 were experimentally detected and identified.

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25

Yuan, Zhen-Yu, Peng Zhang, Shu-kai Yao, et al. "Computational assignments of lattice vibrations of ice Ic." RSC Advances 7, no. 58 (2017): 36801–6. http://dx.doi.org/10.1039/c7ra04332e.

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Herein,viathe first-principles density functional theory, CASTEP code, we investigated the 15 vibrational normal modes of ferroelectric hydrogen-ordered phase of ice Ic and the two peaks of hydrogen bond are clarified.

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26

Michaelian, K. H. "The Raman spectrum of kaolinite #9 at 21°C." Canadian Journal of Chemistry 64, no. 2 (1986): 285–94. http://dx.doi.org/10.1139/v86-048.

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The Raman spectrum of kaolinite #9, a layer silicate of composition Al2Si2O5(OH)4 from Mesa Alta, New Mexico, USA, is reported and compared to previously published Raman and infrared spectra, as well as calculated lattice vibration frequencies, of other kaolinite samples. In the OH stretching region, a Raman band is observed at 3684 cm−1, a frequency which is generally unknown in infrared spectra of kaolinite. The two most likely origins of this band are (a) uncoupled inner-surface hydroxyl stretching, and (b) transverse/longitudinal splitting involving the 3695 cm−1 band, which occurs in both Raman and infrared spectra of kaolinite. The existing data do not conclusively show which of these explanations is correct. In the lattice vibration region, most of the observed Raman bands of kaolinite #9 have been tentatively assigned by comparison with published frequency calculations and existing assignments of infrared spectra of various kaolinites. The descriptions of many of the vibrational modes are approximate, partly because extensive mixing of vibrations makes a simple description of them impossible.

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27

Koteras, Kacper, Jakub Gawraczyński, Mariana Derzsi, Zoran Mazej, and Wojciech Grochala. "Lattice Dynamics of KAgF3 Perovskite, Unique 1D Antiferromagnet." Chemistry 3, no. 1 (2021): 94–103. http://dx.doi.org/10.3390/chemistry3010007.

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Theoretical DFT calculations using GGA+U and HSE06 frameworks enabled vibrational mode assignment and partial (atomic) phonon DOS determination in KAgF3 perovskite, a low-dimensional magnetic fluoroargentate(II). Twelve bands in the spectra of KAgF3 were assigned to either IR active or Raman active modes, reaching excellent correlation with experimental values (R2 > 0.997). Low-temperature Raman measurements indicate that the intriguing spin-Peierls-like phase transition at 230 K is an order–disorder transition and it does not strongly impact the vibrational structure of the material.

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28

Rafailov, P. M., R. Todorov, V. Marinova, D. Z. Dimitrov, and M. M. Gospodinov. "Optical spectroscopic study of Ru and Rh doped Bi12TiO20 crystals." Bulgarian Chemical Communications 51, no. 2 (2019): 219–23. http://dx.doi.org/10.34049/bcc.51.2.4856.

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Bi12TiO20 (BTO) single crystals in pristine state and doped with ruthenium and rhodium are grown by the top-seeded solution growth method and characterized by optical and Raman spectroscopy. The effect of doping on the vibrational and optical properties is studied. The doped crystals show higher absorption in the visible spectral range and higher transmission in the near infrared region as compared to pristine BTO. The performed spatially resolved polarized Raman measurements reveal no significant doping-induced shift of vibrational modes while differences in the LO/TO intensity ratio of the tetrahedral asymmetric stretching vibration are encountered. The observations are discussed in terms of lattice ordering and dopant oxidation states.

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29

Nishiguchi, Norihiko, and Tetsuro Sakuma. "Lattice vibrational spectrum and possible existence of localized modes of the two-dimensional Penrose lattice." Physical Review B 38, no. 11 (1988): 7370–77. http://dx.doi.org/10.1103/physrevb.38.7370.

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Abdullina, D. U., M. N. Semenova, A. S. Semenov, et al. "Stability of in-plane delocalized vibrational modes in triangular Morse lattice." IOP Conference Series: Materials Science and Engineering 447 (November 21, 2018): 012060. http://dx.doi.org/10.1088/1757-899x/447/1/012060.

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31

Li, Jingyu, Peng-Fei Liu, Chi Zhang, et al. "Lattice vibrational modes and phonon thermal conductivity of single-layer GaGeTe." Journal of Materiomics 6, no. 4 (2020): 723–28. http://dx.doi.org/10.1016/j.jmat.2020.04.005.

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Zhou, Tao, Yidong Wu, Juncheng Cao, et al. "Research on the Terahertz Absorption Spectra of Histidine Enantiomer (L) and its Racemic Compound (DL)." Applied Spectroscopy 71, no. 2 (2016): 194–202. http://dx.doi.org/10.1177/0003702816669728.

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Terahertz time-domain spectroscopy (THz-TDS) is used to investigate the absorption spectra of polycrystalline L- and DL-histidine in the frequency range of 10–100 cm-1. The spectra exhibit distinct differences in peak frequencies between the enantiomer (L-histidine) and racemic compound (DL-histidine). The observed spectral differences are attributed to the intermolecular interactions. With the density function theory (DFT) method, the frequencies of vibrational modes of L-histidine and DL-histidine in the THz range are calculated and well assigned according to the measured spectra. The origin of the observed vibrational modes is found to be non-localized and of a collective (phonon-like) nature, which points to the lattice and skeleton vibrations mediated by the hydrogen bond. Furthermore, we propose and demonstrate a method for determining the composition ratio of histidine mixtures based on the THz absorption spectra.

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33

Butler, K. T., B. J. Dringoli, L. Zhou, P. M. Rao, A. Walsh, and L. V. Titova. "Ultrafast carrier dynamics in BiVO4 thin film photoanode material: interplay between free carriers, trapped carriers and low-frequency lattice vibrations." Journal of Materials Chemistry A 4, no. 47 (2016): 18516–23. http://dx.doi.org/10.1039/c6ta07177e.

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We explore ultrafast carrier dynamics and interactions of photoexcited carriers with lattice vibrational modes in BiVO<sub>4</sub> using time-resolved terahertz spectroscopy and first-principles phonon spectrum calculations.

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34

Ullah, Aman, José J. Baldoví, Alejandro Gaita-Ariño, and Eugenio Coronado. "Insights on the coupling between vibronically active molecular vibrations and lattice phonons in molecular nanomagnets." Dalton Transactions 50, no. 32 (2021): 11071–76. http://dx.doi.org/10.1039/d1dt01832a.

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35

Berlie, Adam, та Hamish Cavaye. "The low energy phonon modes of the hydrogenated and deuterated π-conjugated system 7,7,8,8-tetracyanoquinodimethane: an inelastic neutron scattering study". Physical Chemistry Chemical Physics 23, № 4 (2021): 2899–905. http://dx.doi.org/10.1039/d0cp06253g.

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TCNQ is a fascinating molecule with potential for optical, electronic and magnetic materials. Our work studies the low energy lattice modes of the parent compound to further understand the vibrational properties including their temperature dependence.

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Lutz, H. D., J. Himmrich, and H. Haeuseler. "Lattice Vibration Spectra. LX. Lattice Dynamical Calculations on Spinel Type MCr2S4 (M = Mn, Fe, Cd)." Zeitschrift für Naturforschung A 45, no. 7 (1990): 893–902. http://dx.doi.org/10.1515/zna-1990-0710.

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AbstractLattice dynamical calculations of the spinel type MCr2S4 (M = Mn, Fe, Cd) have been done using various potential models (short-range, rigid-ion, polarizable-ion). The main results are that (i) the vibrational modes (eigenvectors) and potential energy distributions of the Raman and IR allowed phonon modes of the three chromium sulfides are very similar, (ii) the A-X and B-X short-range force constants (referring to AB2X4) strongly depend on the structural parameter u, i.e., the tetrahedral A-X force constants are smaller than the respective octahedral B-X ones opposite to previous calculations on the basis of an ideal spinel structure with u = 0.25, (iii) bending force constants (X-A-X and X-B-X), but not X-X and B-B repulsive forces, are negligible, (iv) in the case of the breathing mode of the tetrahedral AX4 unit (species A1g) the demand on B-X and X-X (stretching and repulsion) forces is larger than that on the A-X force, and (v) the effective dynamic charges of the bivalent metal ions are nearly zero.

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Maczka, M., A. Sieradzki, R. Poprawski, K. Hermanowicz, and J. Hanuza. "Lattice dynamics calculations and temperature dependence of vibrational modes of ferroelastic Li2TiGeO5." Journal of Physics: Condensed Matter 18, no. 7 (2006): 2137–47. http://dx.doi.org/10.1088/0953-8984/18/7/003.

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Card, A., M. Mokim, and F. Ganikhanov. "Resolving fine spectral features in lattice vibrational modes using femtosecond coherent spectroscopy." AIP Advances 6, no. 2 (2016): 025115. http://dx.doi.org/10.1063/1.4942478.

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Maksimov, I. L., and D. P. Kaznov. "Localized vibrational modes in a quasi-one-dimensional lattice with a macrodefect." Solid State Communications 121, no. 6-7 (2002): 305–8. http://dx.doi.org/10.1016/s0038-1098(02)00005-4.

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GuangHui, Zhou, Yan JiaRen, and Tang Yi. "Possible Propagating Intrinsic Localized Vibrational Modes for One-Dimensional Klein–Gordon Lattice." Communications in Theoretical Physics 32, no. 4 (1999): 537–44. http://dx.doi.org/10.1088/0253-6102/32/4/537.

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Aharon, S., та A. Brokman. "Lattice dynamics study of vibrational modes in gold Σ5[001] twist boundary". Acta Metallurgica et Materialia 39, № 11 (1991): 2489–96. http://dx.doi.org/10.1016/0956-7151(91)90063-7.

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McCluskey, M. D., Eugene E. Haller, W. Walukiewicz, and P. Becla. "Resonant Interaction Between Local Vibrational Modes and Extended Lattice Phonons in AlSb." Materials Science Forum 258-263 (December 1997): 1247–52. http://dx.doi.org/10.4028/www.scientific.net/msf.258-263.1247.

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Hoffman, Alexander E. J., Jelle Wieme, Sven M. J. Rogge, Louis Vanduyfhuys, and Veronique Van Speybroeck. "The impact of lattice vibrations on the macroscopic breathing behavior of MIL-53(Al)." Zeitschrift für Kristallographie - Crystalline Materials 234, no. 7-8 (2019): 529–45. http://dx.doi.org/10.1515/zkri-2018-2154.

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Abstract The mechanism inducing the breathing in flexible metal-organic frameworks, such as MIL-53(Al), is still not fully understood. Herein, the influence of lattice vibrations on the breathing transition in MIL-53(Al) is investigated to gain insight in this phenomenon. Through solid-state density-functional theory calculations, the volume-dependent IR spectrum is computed together with the volume-frequency relations of all vibrational modes. Furthermore, important thermodynamic properties such as the Helmholtz free energy, the specific heat capacity, the bulk modulus, and the volumetric thermal expansion coefficient are derived via these volume-frequency relations using the quasi-harmonic approximation. The simulations expose a general volume-dependency of the vibrations with wavenumbers above 300 cm−1 due to their localized nature. In contrast, a diverse set of volume-frequency relations are observed for vibrations in the terahertz region (<300 cm−1) containing the vibrations exhibiting collective behavior. Some terahertz vibrations display large frequency differences over the computed volume range, induced by either repulsion or strain effects, potentially triggering the phase transformation. Finally, the impact of the lattice vibrations on the thermodynamic properties is investigated. This reveals that the closed pore to large pore phase transformation in MIL-53(Al) is mainly facilitated by terahertz vibrations inducing rotations of the organic linker, while the large pore to closed pore phase transformation relies on two framework-specific soft modes.

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Schutte, C. J. H., and J. A. Pretorius. "A computational study of the molecular and crystal structure and selected physical properties of octahydridosilasequioxane, (Si 2 O 3 H 2 ) 4 . II. Vibrational analysis." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, no. 2139 (2011): 851–70. http://dx.doi.org/10.1098/rspa.2011.0473.

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A computational study of octahydridosilasequioxane, Si 8 O 12 H 8 , as a free molecule and when embedded in the unit cell R -3, Z =3, showed that the point group of the free molecule is indeed O h , but that its crystal symmetry is reduced to C 3i . Since the molecular and site-group symmetries influence the vibrational structure of a molecule, a full computational vibrational analysis of the isolated molecule and when embedded in the crystal lattice, is reported here. The analysis of the free molecular spectra given here agrees with that of its experimental infra-red (IR)-spectra and allows the assignment of all the vibrational modes, while the computed phonon dispersion of the crystal confirms the assignment of the internal vibrational modes of the molecule in the crystal. The computed and experimental IR spectra as well as Raman spectra show no indication of serious vibrational intermolecular coupling owing to the presence of multiple molecules in the unit cell. This may be the result of a weak intermolecular vibrational coupling in the solid state, which may feature in the low-frequency modes.

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Nash, Lisa M., Dustin Kleckner, Alismari Read, Vincenzo Vitelli, Ari M. Turner, and William T. M. Irvine. "Topological mechanics of gyroscopic metamaterials." Proceedings of the National Academy of Sciences 112, no. 47 (2015): 14495–500. http://dx.doi.org/10.1073/pnas.1507413112.

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Topological mechanical metamaterials are artificial structures whose unusual properties are protected very much like their electronic and optical counterparts. Here, we present an experimental and theoretical study of an active metamaterial—composed of coupled gyroscopes on a lattice—that breaks time-reversal symmetry. The vibrational spectrum displays a sonic gap populated by topologically protected edge modes that propagate in only one direction and are unaffected by disorder. We present a mathematical model that explains how the edge mode chirality can be switched via controlled distortions of the underlying lattice. This effect allows the direction of the edge current to be determined on demand. We demonstrate this functionality in experiment and envision applications of these edge modes to the design of one-way acoustic waveguides.

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Verma, V., D. Chionis, A. Dokhane, and H. Ferroukhi. "MODELLING AND ANALYSIS OF FUEL ASSEMBLY VIBRATIONAL MODES IN PWRS USING SIMULATE-3K." EPJ Web of Conferences 247 (2021): 21008. http://dx.doi.org/10.1051/epjconf/202124721008.

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Some of the KWU pre-KONVOI PWRs operating across Europe saw a systematic increase in the neutron noise levels over several cycles in the last decade, and subsequently, core internals’ movements, especially vibrations of fuel assemblies with specific designs were identified as one of the plausible causes. Therefore, it is important to develop computational methods that can allow to investigate and predict the reactor noise response to fuel assemblies vibrations. To this aim, the 3D nodal reactor dynamics code SIMULATE-3K is used at PSI with a special module called the ‘assembly vibration model’ that imitates time-dependent motions of fuel assemblies by dynamically modifying the water-gaps surrounding the laterally moving fuel assemblies. The varying water-gaps are represented by the variation in the corresponding two-group macroscopic cross sections generated using the lattice code CASMO-5 in 2D. The studies conducted so far to assess the methodology for full core noise simulations were based on assuming vibrations of a clamped-free cluster of fuel assemblies that are unsupported from both ends. However, as this represents a non-physical movement, further developments were made at PSI to allow simulating more realistic movements of fuel assemblies such as the cantilevered mode vibration. The updated methodology, along with evaluations of the simulated noise response to realistic vibration modes, is presented in this paper. Results show that, as expected, the radial and axial neutron noise behaviour follow the vibration pattern of the imposed time-dependent axial functions corresponding to the natural oscillation modes of the fuel assemblies, thereby providing confidence in the application of the developed methodology for numerical neutron noise analyses of the PWR cores.

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Itoh, H., B. Chazallon, H. Schober, K. Kawamura, and W. F. Kuhs. "Inelastic neutron scattering and molecular dynamics studies on low-frequency modes of clathrate hydrates." Canadian Journal of Physics 81, no. 1-2 (2003): 493–501. http://dx.doi.org/10.1139/p03-034.

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Low-frequency modes of gas hydrates with Xe, Ar, O2, and N2 atoms/molecules have been studied by inelastic neutron-scattering and molecular dynamics simulations. Type I and type II clathrate hydrates show some small but significant differences of the low-frequency host contribution to the density of states. Both differ markedly from that of ice Ih and depend only weakly on the guest. The vibrational modes associated with Xe atoms were observed at 2.2, 2.9, and 4.0 meV (T = 100 K). They are in good agreement with predictions from molecular dynamics simulations. In the case of N2 hydrate we found a well-defined peak at about 2 meV, which shows a remarkable shift to higher frequency with increasing temperature. This peak and a broad peak that is overlapped with the host lattice modes (6.5 and 10.5 meV) are assigned to the vibration of N2 molecules in the large and small cages, respectively. The calculated vibrational spectra of N2 molecules in doubly occupied large cages show a significant distinct spectral distribution. The anharmonic shift of the guest atoms in large cages is significantly less pronounced in Xe hydrates suggesting that guest-host interactions can vary considerably from one system to another. PACS Nos.: 82.75-z, 78.70N, 71.15Pd, 63

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Liu, Jiu Li, Ping Qian, Yao Wen Hu, Li Jun Bai, and Jiang Shen. "Structural Simulation and Lattice Vibration of a₃Ni₅Al₁₉ (A = Th, U)." Advanced Materials Research 233-235 (May 2011): 2310–14. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.2310.

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An atomistic simulation is presented on the phase stability and lattice parameters of the new actinide intermetallic compounds A3Ni5Al19(A = Th, U). Calculations are based on a series of interatomic pair potentials related to the actinides and transition metals, which are obtained by lattice inversion method. Calculated lattice constants are found to agree with a report in the literature. It is noted that, the total and partial phonon densities of states are first evaluated for the A3Ni5Al19(A = Th, U) compounds. The analysis for the inverted potentials explains qualitatively the contributions of different atoms to the vibrational modes.

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Bennett, Joseph, Michaella Raglione, Shalisa Oburn, Leonard MacGillivray, Mark Arnold, and Sara Mason. "DFT Computed Dielectric Response and THz Spectra of Organic Co-Crystals and Their Constituent Components." Molecules 24, no. 5 (2019): 959. http://dx.doi.org/10.3390/molecules24050959.

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Terahertz (THz) spectroscopy has been put forth as a non-contact, analytical probe to characterize the intermolecular interactions of biologically active molecules, specifically as a way to understand, better develop, and use active pharmaceutical ingredients. An obstacle towards fully utilizing this technique as a probe is the need to couple features in the THz regions to specific vibrational modes and interactions. One solution is to use density functional theory (DFT) methods to assign specific vibrational modes to signals in the THz region, coupling atomistic insights to spectral features. Here, we use open source planewave DFT packages that employ ultrasoft pseudopotentials to assess the infrared (IR) response of organic compounds and complex co-crystal formulations in the solid state, with and without dispersion corrections. We compare our DFT computed lattice parameters and vibrational modes to experiment and comment on how to improve the agreement between theory and modeling to allow for THz spectroscopy to be used as an analytical probe in complex biologically relevant systems.

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Jiang, Lu, Shu-Kai Yao, Kai Zhang, et al. "Exotic Spectra and Lattice Vibrations of Ice X Using the DFT Method." Molecules 23, no. 11 (2018): 2780. http://dx.doi.org/10.3390/molecules23112780.

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A typical vibrational spectrum in the ice phase has four separate bands: Translation, libration, bending, and stretching. Ice X, the final ice phase under high pressure, shows an exotic vibrational spectrum. Based on harmonic approximation, an ideal crystal of ice X has one peak, at 998 cm−1, for Raman scattering and two peaks, at 450 cm−1 and 1507 cm−1, for infrared absorption in this work. These three characteristic peaks are indicators of the phase transition between ice VII and VIII and ice X. Despite many experimental and theoretical works on ice X, only this study has clearly indicated these characteristic peaks in the region of the IR band. The phonon density of states shows quite different features than ice VIII, which could be verified by inelastic neutron scattering in the future. The dynamic processes of 15 vibrational normal modes are discussed and the typical hydrogen bonds are missing.

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