Lattice dynamics of alkali hydrides and euterides with the NaCl type structure

Dyck, W

doi:10.1088/0022-3719/14/29/008

Cited by 25 publications

(32 citation statements)

References 32 publications

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“…Despite the differences between our Li+-Li+ interaction and an unexpectedly strong interaction found by DJ [8], there is similarity of interaction strengths between other second neighbours. Thus the dispersion curves presented here are mainly determined by the nearest neighbour interactions and also the effects arising from the electronic polarizability of ions.…”

Section: Dynand Propertiescontrasting

confidence: 70%

Hydrides and Deuterides of Lithium and Sodium. I. Model Potentials and Their Use in Perfect Lattice

Haque¹,

Islam²

1990

Physica Status Solidi (b)

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An interionic potential model is developed for lighter and heavier alkali hydrides and deuterides. The method uses a combination of theoretical techniques, empirical fit, and a few plausible assumptions. An assessment of the derived potentials is made by calculating the lattice statics and dynamics of the crystals and by comparing both with experiment (where available) and with other calculations. The potentials are found to describe the elastic and dielectric properties reasonably well. The phonon dispersion curves of hydride and deuteride of sodium are compared with the calculations of Dyck and Jex based on force constant model approach and the results are discussed. The need for further experiments on heavier hydrides and deuterides is stressed.Es wird ein Interionenpotentialmodell fur leichtere und schwerere Alkalihydride und -deuteride entwickelt. Die Methode benutzt eine Kombination von theoretischen Techniken, empirischer Anpassung und einigen wenigen plausiblen Annahmen. Eine Einschatzung der abgeleiteten Potentiale wird durch Berechnung der Gitterstatik und -dynamik der Kristalle und durch Vergleich sowohl mit Experimenten (wenn vorhanden) als auch mit anderen Berechnungen durchgefiihrt. Es wird gefunden, daI3 die Potentiale die elastischen und dielektrischen Eigenschaften verhaltnismaBig gut beschreiben. Die Phononendispersionskurven der Hydride und Deuteride von Natrium werden mit den von Dyck und Jex auf der Grundlage des Kraftkonstantenmodells durchgefiihrten Berechnungen verglichen und die Ergebnisse diskutiert. Die Notwendigkeit weiterer Experimente an schwereren Hydriden und Deuteriden wird hervorgehoben.

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Section: Dynand Propertiescontrasting

confidence: 70%

Hydrides and Deuterides of Lithium and Sodium. I. Model Potentials and Their Use in Perfect Lattice

Haque¹,

Islam²

1990

Physica Status Solidi (b)

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“…As in the previous section, we look for wave-like solutions of the form 17) where the frequency depends on k, which is now a vector (called the wavevector). Substitution into Eq.…”

Section: Phonons In a 3d Crystalmentioning

confidence: 99%

“…Unfortunately the model for the interactions between atoms here is too simplified to be generalisable to more complex solids. More sophisticated models have been addressed in a number of studies, considering models to account for polarisation of atomic charges [15,16] and extended interactions beyond nearest neighbours [17]. Many more adjustable parameters must be introduced to the model of interatomic forces to account for these interactions, and the simplicity of the model is lost.…”

Section: Simple Parameterisation For Ionic Systemsmentioning

confidence: 99%

Computational Methods for the Assignment of Vibrational Modes in Crystalline Materials

Tomerini

Day

2012

Terahertz Spectroscopy and Imaging

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In this chapter we provide a description of the computational tools used for the calculation of the terahertz absorption spectrum of a crystalline material, with a particular focus on molecular crystals. We explain using examples why it is not correct to use the normal modes of vibration of an isolated molecule to understand the vibrational spectrum of a material in the terahertz range, but that the features in this spectral region are largely related to intermolecular interactions. It is, therefore, necessary to use methods that consider the periodicity of the crystal structure. We describe the two main methods used for the calculation of the vibrational frequencies and their absorption intensities of a crystal: lattice dynamics and molecular dynamics, providing examples showing the benefits and limitations of each method.

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“…A complete elaboration of these topics from the first principles is indispensable for understanding of H-behavior in metallic systems in general. Moreover, extensive data about metal hydrides have been obtained and explained using various, and sometimes contradictory, concepts [15][16][17][18][20][21][22][23][24][25][26][33][34][35][36][37][38][39]. However, a coherent approach valid for all metal hydrides is still missing.…”

Section: Introductionmentioning

confidence: 99%

“…For that purpose we extended our previous experimental [33,44,45], and known numerical [20,23,32,44,65] results by first-principle calculations of the electronic structures of various metal hydrides using the Full Potential Augmented Plane Waves extended (FP-APW+lo) and the Full Potential Linearized Augmented Plane Waves (FP-LAPW+LO) with addition of local orbitals methods, as implemented in the WIEN2k software package [73], and the pseudopotentials method, as implemented in Abinit software package.…”

Section: Introductionmentioning

confidence: 99%

Electronic Principles of Hydrogen Incorporation and Dynamics in Metal Hydrides

et al. 2012

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An approach to various metal hydrides based on electronic principles is presented. The effective medium theory (EMT) is used to illustrate fundamental aspects of metal-hydrogen interaction and clarify the most important processes taking place during the interaction. The elaboration is extended using the numerous existing results of experiment and calculations, as well as using some new material. In particular, the absorption/desorption of H in the Mg/MgH 2 system is analyzed in detail, and all relevant initial structures and processes explained. Reasons for the high stability and slow sorption in this system are noted, and possible solutions proposed. The role of the transition-metal impurities in MgH 2 is briefly discussed, and some interesting phenomena, observed in complex intermetallic compounds, are mentioned. The principle mechanism governing the Li-amide/imide transformation is also discussed. Latterly, some perspectives for the metal-hydrides investigation from the electronic point of view are elucidated.

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Lattice dynamics of alkali hydrides and euterides with the NaCl type structure

Cited by 25 publications

References 32 publications

Hydrides and Deuterides of Lithium and Sodium. I. Model Potentials and Their Use in Perfect Lattice

Hydrides and Deuterides of Lithium and Sodium. I. Model Potentials and Their Use in Perfect Lattice

Computational Methods for the Assignment of Vibrational Modes in Crystalline Materials

Electronic Principles of Hydrogen Incorporation and Dynamics in Metal Hydrides

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