This article reviews the current status of lattice-dynamical calculations in crystals, using density-functional perturbation theory, with emphasis on the plane-wave pseudopotential method. Several specialized topics are treated, including the implementation for metals, the calculation of the response to macroscopic electric fields and their relevance to long-wavelength vibrations in polar materials, the response to strain deformations, and higher-order responses. The success of this methodology is demonstrated with a number of applications existing in the literature.

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Phonons and related crystal properties from density-functional perturbation theory

Annual review of condensed matter physics

We introduce density functional theory and review recent progress in its application to transition metal chemistry. Topics covered include local, meta, hybrid, hybrid meta, and range-separated functionals, band theory, software, validation tests, and applications to spin states, magnetic exchange coupling, spectra, structure, reactivity, and catalysis, including molecules, clusters, nanoparticles, surfaces, and solids.

Density functional theory for transition metals and transition metal chemistry

We present a Raman scattering study of wurtzite $\mathrm{ZnO}$ over a temperature range from 80 to $750\phantom{\rule{03em}{0ex}}\mathrm{K}$ Second-order Raman features are interpreted in the light of recent ab initio phonon density of states calculations The temperature dependence of the Raman intensities allows the assignment of difference modes to be made unambiguously Some weak, sharp Raman peaks are detected whose temperature dependence suggests they may be due to impurity modes High-resolution spectra of the ${E}_{2}^{\mathrm{high}}$, ${A}_{1}(\mathrm{LO})$, and ${E}_{1}(\mathrm{LO})$ modes were recorded, and an analysis of the anharmonicity and lifetimes of these phonons is carried out The ${E}_{2}^{\mathrm{high}}$ mode displays a visibly asymmetric line shape This can be attributed to anharmonic interaction with transverse and longitudinal acoustic phonon combinations in the vicinity of the $K$ point, where the two-phonon density of states displays a sharp edge around the ${E}_{2}^{\mathrm{high}}$ frequency The temperature dependence of the linewidth and frequency of the ${E}_{2}^{\mathrm{high}}$ mode is well described by a perturbation-theory renormalization of the harmonic ${E}_{2}^{\mathrm{high}}$ frequency resulting from the interaction with the acoustic two-phonon density of states In contrast, the ${A}_{1}(\mathrm{LO})$ and ${E}_{1}(\mathrm{LO})$ frequencies lie in a region of nearly flat two-phonon density of states, and they exhibit a nearly symmetric Lorentzian line shape with a temperature dependence that is well accounted for by a dominating asymmetric decay channel

Temperature dependence of Raman scattering in ZnO

Atomic layer deposition (ALD) is gaining attention as a thin film deposition method, uniquely suitable for depositing uniform and conformal films on complex three-dimensional topographies. The deposition of a film of a given material by ALD relies on the successive, separated, and self-terminating gas–solid reactions of typically two gaseous reactants. Hundreds of ALD chemistries have been found for depositing a variety of materials during the past decades, mostly for inorganic materials but lately also for organic and inorganic–organic hybrid compounds. One factor that often dictates the properties of ALD films in actual applications is the crystallinity of the grown film: Is the material amorphous or, if it is crystalline, which phase(s) is (are) present. In this thematic review, we first describe the basics of ALD, summarize the two-reactant ALD processes to grow inorganic materials developed to-date, updating the information of an earlier review on ALD [R. L. Puurunen, J. Appl. Phys. 97, 121301 (2005)], and give an overview of the status of processing ternary compounds by ALD. We then proceed to analyze the published experimental data for information on the crystallinity and phase of inorganic materials deposited by ALD from different reactants at different temperatures. The data are collected for films in their as-deposited state and tabulated for easy reference. Case studies are presented to illustrate the effect of different process parameters on crystallinity for representative materials: aluminium oxide, zirconium oxide, zinc oxide, titanium nitride, zinc zulfide, and ruthenium. Finally, we discuss the general trends in the development of film crystallinity as function of ALD process parameters. The authors hope that this review will help newcomers to ALD to familiarize themselves with the complex world of crystalline ALD films and, at the same time, serve for the expert as a handbook-type reference source on ALD processes and film crystallinity.

Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trends

The anharmonic lifetimes of zone-center optical phonons in C, Si, and Ge are calculated along with their temperature and pressure dependences, using third-order density-functional perturbation theory. Our basic ingredients are by-products of a standard linear-response calculation of phonon dispersions in the harmonic approximation, resulting in a similarly good agreement with experiments. The microscopic mechanisms responsible for the decay are revealed and shown to be different for different materials and to depend sensitively on the applied pressure.

Anharmonic Phonon Lifetimes in Semiconductors from Density-Functional Perturbation Theory.

We examine the dependence on size distribution of the Raman line shape of optical vibron modes in CdSe dots. A detailed comparison with the theory of electron-hole correlated Raman scattering in spherical quantum dots, which includes LO-confined modes, is carried out. The obtained CdSe vibron frequencies are found to map well on the ab initio calculated LO phonon dispersion relations of wurtzite CdSe along the [001] direction of the Brillouin zone.

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Optical vibrons in CdSe dots and dispersion relation of the bulk material

In this work we present an ab initio calculation of the Raman linewidth of transverse and longitudinal phonon in zinc-blende semiconductors GaAs, AlAs, GaP, and InP. We propose a simple approximation that permits us to calculate the longitudinal linewidths with the same computational effort as the transverse ones. The microscopic mechanisms responsible for the decay are analyzed and discussed. The temperature dependence of the linewidths is computed. Our results are in good agreement with available experimental data up to room temperature for both transverse and longitudinal optical modes and give reliable predictions in materials difficult to study experimentally.

Phonon linewidth in iii-v semiconductors from density-functional perturbation theory

We present an ab initio pseudopotential calculation of thermodynamic properties of aluminum and tungsten. The difference of almost one order of magnitude of the experimental linear thermal expansion coefficients of these materials is well reproduced by our calculations and explained in terms of microscopic quantities. The specific heat is reported and compared with available experimental data. Mode-Gr\"uneisen parameters, Debye temperature, and temperature dependence of isothermal and adiabatic bulk modulus as well as the pressure dependence of compressibility complete the work.

Ab initio thermodynamics of metals: Al and W

The dependence of the crystal lattice constant on isotopic substitution of atomic masses is investigated in GaAs and ZnSe using perturbation theory in a density-functional framework. The temperature dependence of the derivatives of the lattice constant with respect to both the anion and the cation mass is computed. Results for additional lattice properties, such as the linear thermal expansion coefficients and mode Gr\"uneisen parameters, are reported and compared with available experimental data. Chemical trends are discussed. \textcopyright{} 1996 The American Physical Society.

Alberto Debernardi

Papers

Anharmonic Phonon Lifetimes in Semiconductors from Density-Functional Perturbation Theory.

Optical vibrons in CdSe dots and dispersion relation of the bulk material

Phonon linewidth in iii-v semiconductors from density-functional perturbation theory

Ab initio thermodynamics of metals: Al and W

Isotopic effects on the lattice constant in compound semiconductors by perturbation theory : an ab initio calculation