Molekulardynamik

Haberlandt, R.; Fritzsche, Siegfried; Peinel, Gustav; Heinzinger, K.

doi:10.1007/978-3-322-90870-4

Cited by 51 publications

(17 citation statements)

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“…[42] If we could know with absolute certainty the spring constant, f, of the one-dimensional H or Li-H chain mentioned already, for example, then a (microcanonical) ensemble of several thousand H or Li atoms in a given volume could be prepared, and its evolution [43] would be monitored over time in the context of molecular dynamics. [44,45] Alternately, all the nuclear configurations could be randomized according to the Monte Carlo procedure, [46] and the thermodynamic equilibrium ascertained in a purely stochastic way. Both procedures are quite plausible and computationally the last resort, and for that very reason a much simpler approach is apparent, which is positioned closer to the electronicstructure theory of solids:…”

Section: Free Phonon Energymentioning

confidence: 99%

Ab Initio Thermochemistry of Solid‐State Materials

et al. 2010

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In this contribution we introduce an electronic-structure-theory-based approach to a quantum-chemical thermochemistry of solids. We first deal with local and collective atomic displacements and explain how to calculate these. The fundamental importance of the phonons, their dispersion relations, their experimental determination as well as their calculation is elucidated, followed by the systematic construction of the thermodynamic potentials on this basis. Subsequently, we provide an introduction for practical computation as well as a critical analysis of the level of accuracy obtainable. We then show how different solid-state chemistry problems can be solved using this approach. Among these are the calculation of activation energies in perovskite-like oxides, but we also consider the use of theoretical vibrational frequencies for determining crystal structures. The pressure and temperature polymorphism of elemental tin which has often been classically described is also treated, and we energetically classify the metastable oxynitrides of tantalum. We also demonstrate, using the case of high-temperature superconductors, that such calculations may be used for an independent evaluation of thermochemical data of unsatisfactory accuracy. Finally, we show the present limits and the future challenges of the theory.

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Section: Free Phonon Energymentioning

confidence: 99%

Ab Initio Thermochemistry of Solid‐State Materials

et al. 2010

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“…The pair correlation function g(r) = density͑r͒/density͑0͒ describes the radial distribution function of the atoms in the crystal on an atomic scale with density͑0͒ as the mean density of the system and density ͑r͒ the probability density to find an atom at the distance r. Therefore, different crystalline structures lead to different characteristic atoms distribution patterns and amorphous structures do not show an or- dered distribution. 23 The correlation length is the thermodynamic parameter of the system which defines the critical size of the ordered phase which is needed to stabilize the phase: g(r) ϳ exp͑A/correlation length͒, with A as a scaling factor. If the region is below this critical size it is still amorphous, even though it may have local ordering.…”

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confidence: 99%

Low-Temperature Growth of Polycrystalline Ge Films on SiO2 Substrate by HDPCVD

Yang

Shieh

Hsu

et al. 2005

Electrochemical and Solid-State Letters

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Pure and high-quality polycrystalline Ge films have been deposited directly onto fully SiO 2 covered substrates by high-density plasma chemical vapor deposition ͑HDPCVD͒ system. Only a tiny amount of O and C near the surface has been observed from X-ray photoelectron spectroscopy and Auger electron spectroscopy data, which may come from surface oxidation and contamination. Very pure Ge composition has been achieved in the bulk of the films. The cubic structure with primarily ͑111͒, ͑220͒, and ͑311͒ orientations of the Ge films is mainly composed of fine grains and can be unambiguously identified from X-ray diffraction patterns. Furthermore, successful Ge film depositions with nearly no incubation time are demonstrated using a mixture of GeH 4 /H 2 as process gas at 400°C. Thickness vs. time analysis was performed by high-resolution transmission electron microscopy. The HDPCVD technique used was able to provide a simple, powerful, and reliable approach in the fabrication of polycrystalline Ge thin film transistors.Ge has attracted more and more attention due to its wide applications in ultralarge scale integration ͑ULSI͒ and booming nanotechnologies. Ge/Si and SiGe/Si heterostructures have been used in high-performance devices because of their higher electron and hole mobility compared to Si. 1-5 Three-dimensional Ge islands formed on Si surfaces by solid-phase epitaxy technique have also been demonstrated to have great potential in the fabrication of nanostructures. 6 In addition, Ge-on-insulators ͑GOI͒ is especially desired for achieving extremely high performance metal oxide silicon field-effect transistors ͑MOSFET͒ with sufficiently low leakage current. 7,8 However, for thin film transistor ͑TFT͒ applications, successful Ge thin film deposition on SiO 2 substrates using chemical vapor deposition ͑CVD͒ techniques has not been demonstrated so far due to the extremely long incubation times needed. [9][10][11][12][13][14][15] In the present study, we demonstrate the deposition of polycrystalline Ge films directly onto fully SiO 2 covered Si substrates with nearly no incubation time by using high-density plasma CVD ͑HD-PCVD͒ technique at 400°C. X-ray photoelectron spectroscopy ͑XPS͒ and Auger electron spectroscopy ͑AES͒ analyses show that the deposition of very pure Ge thin films can be achieved without significantly detectable O and C incorporations. X-ray diffraction ͑XRD͒ patterns clearly illustrate that the deposited Ge films are of cubic structure with primarily ͑111͒, ͑220͒, and ͑311͒ orientations, respectively, and are mainly composed of small grains with sizes around 14 nm calculated from full width at half-maximum ͑fwhm͒. Moreover, the results of high-resolution transmission electron microscopy ͑HRTEM͒ analysis firmly show that only very short incubation time is needed for the deposition. Because CVD has the advantage of uniformity control over other techniques such as sputtering 16 and e-gun deposition, 17,18 which is highly important in mass production, this technique, therefore, provides a simple, power...

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“…The probably most commonly used form of the potential of two neutral atoms which are only bound by Van-der-Waals interactions, is the Lennard-Jones (LJ), or (a-b) potential which has the form (Haberland et al, 1995) …”

Section: Non-bonded Interactionsmentioning

confidence: 99%

Introduction to Molecular Dynamics Simulations: Applications in Hard and Soft Condensed Matter Physics

Steinhauser¹

2012

Molecular Dynamics - Studies of Synthetic and Biological Macromolecules

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Molekulardynamik

Cited by 51 publications

References 0 publications

Ab Initio Thermochemistry of Solid‐State Materials

Ab Initio Thermochemistry of Solid‐State Materials

Low-Temperature Growth of Polycrystalline Ge Films on SiO2 Substrate by HDPCVD

Introduction to Molecular Dynamics Simulations: Applications in Hard and Soft Condensed Matter Physics

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