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We performed ab initio lattice-dynamics calculations of frame-cluster dodecaborides ZrB12 and LuB12. As a whole, our calculated phonon frequencies and atom-projected density of states are consistent with the results of available…

Chemical Physics · Physics 2019-10-22 N. M. Chtchelkatchev , M. V. Magnitskaya , E. S. Clementyev , P. A. Alekseev

The full phonon dispersion relations of lead titanate and lead zirconate in the cubic perovskite structure are computed using first-principles variational density-functional perturbation theory, with ab initio pseudopotentials and a…

Materials Science · Physics 2009-10-31 Ph. Ghosez , E. Cockayne , U. V. Waghmare , K. M. Rabe

We report measurements of the phonon density of states as measured with inelastic x-ray scattering in SmFeAsO$_{1-x}$F$_y$ powders. An unexpected strong renormalization of phonon branches around 23 meV is observed as fluorine is substituted…

We present an \textit{ab initio} framework to calculate anharmonic phonon frequency and phonon lifetime that is applicable to severely anharmonic systems. We employ self-consistent phonon (SCPH) theory with microscopic anharmonic force…

Materials Science · Physics 2015-08-20 Terumasa Tadano , Shinji Tsuneyuki

We have performed a first-principles study of the structural and vibrational properties of the three low-pressure (cubic, tetragonal, and especially monoclinic) phases of ZrO2, with special attention to the computation of the zone-center…

Materials Science · Physics 2009-11-07 Xinyuan Zhao , David Vanderbilt

Lattice thermal conductivities of zincblende- and wurtzite-type compounds with 33 combinations of elements are calculated with the single-mode relaxation-time approximation and linearized phonon Boltzmann equation from first-principles…

Materials Science · Physics 2015-06-30 Atsushi Togo , Laurent Chaput , Isao Tanaka

We report a phonon density of states measurement of $\alpha$-ZnCl$_{2}$ using the coherent inelastic neutron scattering technique and a lattice dynamical calculation in four crystalline phases of ZnCl$_{2}$ using a transferable interatomic…

Materials Science · Physics 2007-05-23 A. Sen , Mala N. Rao , R Mittal , S. L. Chaplot

We present a fully automated framework for extracting interatomic force constants (IFCs) directly from X-ray thermal diffuse scattering (TDS) data. By formulating scattering intensity as a differentiable function of a symmetry-reduced IFC…

Computational Physics · Physics 2026-03-31 Klara Suchan , Shaswat Mohanty , Hanfeng Zhai , Wei Cai

A spectrally formulated finite element analysis based methodology has been proposed to calculate phononic band structure of reticulated honeycomb lattices having translationally invariant repetitive elements called unit cells. Bloch…

Materials Science · Physics 2015-09-30 Sushovan Mukherjee , S. Gopalakrishnan

The crystal structure and phonon dynamics of pentacene is computed with the Quasi Harmonic Lattice Dynamics (QHLD) method, based on atom-atom potential. We show that two crystalline phases of pentacene exist, rather similar in thermodynamic…

Conventional methods to calculate the thermodynamics of crystals evaluate the harmonic phonon spectra and therefore do not work in frequent and important situations where the crystal structure is unstable in the harmonic approximation, such…

Statistical Mechanics · Physics 2009-11-13 P. Souvatzis , O. Eriksson , M. I. Katsnelson , S. P. Rudin

The ferropnictide superconductors exhibit a sensitive interplay between the lattice and magnetic degrees of freedom, including a number of phonon modes that are much softer than predicted by nonmagnetic calculations using density functional…

Superconductivity · Physics 2014-03-13 D. Parshall , R. Heid , J. L. Niedziela , Th. Wolf , M. B. Stone , D. L. Abernathy , D. Reznik

We study squeezed quantum states of phonons, which allow the possibility of modulating the quantum fluctuations of atomic displacements below the zero-point quantum noise level of coherent phonon states. We calculate the corresponding…

Condensed Matter · Physics 2009-10-28 X. Hu , Franco Nori

Optically levitated micro- and nanoparticles are an ideal optomechanical platform for precision measurements, particularly enabling the detection of ultraweak forces. Nevertheless, quantum backaction and inherent instabilities induced by…

Using a combination of density-functional perturbation theory and the itinerant coherent potential approximation, we study the effects of atomic relaxation on the inelastic incoherent neutron scattering cross sections of disordered…

Materials Science · Physics 2009-11-10 Subhradip Ghosh , J. B. Neaton , Armin H. Antons , P. L. Leath , Morrel H. Cohen

We report a study of the lattice dynamics in superconducting NaFeAs (Tc = 8 K) and doped NaFe0.97Co0.03As (Tc = 20 K) using Raman light scattering. Five of the six phonon modes expected from group theory are observed. In contrast with…

Superconductivity · Physics 2016-11-25 Y. J. Um , Yunkyu Bang , B. H. Min , Y. S. Kwon , M. Le Tacon

A detailed description of a method for calculating static linear-response functions in the problem of lattice dynamics is presented. The method is based on density functional theory and it uses linear muffin-tin orbitals as a basis for…

Condensed Matter · Physics 2009-10-28 S. Y. Savrasov

As an alternative to atomistic calculations of long-wavelength acoustic modes of atomically thin layers, which are known to converge very slowly, we propose a quantitatively predictive and physically intuitive approach based on continuum…

Mesoscale and Nanoscale Physics · Physics 2016-11-23 Dan Liu , Arthur G. Every , David Tomanek

We show that phononic frequency conversion can be enhanced by orders of magnitude in piezoelectric systems by heterogeneous integration of high-mobility semiconductor films. A lithium niobate and indium gallium arsenide heterostructure is…

We have performed extensive ab initio calculations to investigate phonon dynamics and their possible role in superconductivity in BaFe2As2 and related systems. The calculations are compared to inelastic neutron scattering data that offer…

Superconductivity · Physics 2009-11-13 M. Zbiri , H. Schober , M. R. Johnson , S. Rols , R. Mittal , Y. Su , M. Rotter , D. Johrendt