| Dielectric Response at THz Frequencies of Mg Water Complexes Interacting with O3 Calculated by Density Functional Theory |
24 Oct 2012 |
67 pages |
| Authors:
L Huang; Samuel G Lambrakos; A Shabaev; L Massa; C Yapijakis; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL MATERIALS SCIENCE
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 | The need for better monitoring of water quality and levels of water contamination implies a need for determining the dielectric response properties of water contaminants with respect to electromagnetic wave excitation. In addition to monitoring contaminants, there is an associated need for monitoring chemical processes whose purpose is deactivation or assistance in the removal of water contaminants. Two naturally occurring water contaminants, which are the result of decaying vegetation, are ... |
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| Origin Of The Structural Phase Transition In Li7La3Zr2O12 |
Sep 2012 |
6 pages |
| Authors:
N Bernstein; M D Johannes; Khang Hoang; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL MATERIALS SCIENCE
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| Garnet-type Li7La3Zr2O12 (LLZO) is a solid electrolyte material with a low-conductivity tetragonal and a high-conductivity cubic phase. Using density-functional theory and variable cell shape molecular dynamics simulations, we show that the tetragonal phase stability is dependent on a simultaneous ordering of the Li ions on the Li sublattice and a volume-preserving tetragonal distortion that relieves internal structural strain. Supervalent doping introduces vacancies into the Li sublattice, increasing the overall entropy ... |
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| Terahertz Spectra of Molecular Clusters of RDX, PETN, and TNT Calculated by Density Functional Theory |
15 Mar 2012 |
51 pages |
| Authors:
L Huang; Samuel G Lambrakos; A Shabaev; L Massa; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL MATERIALS SCIENCE
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| We present calculations of ground state resonance structure associated with molecular clusters of the high explosives RDX, PETN, and TNT using density functional theory (DFT), which is for the construction of parameterized dielectric response functions for excitation by electromagnetic waves at compatible frequencies. These dielectric functions provide for different types of analyses concerning the dielectric response of explosives. In particular, these dielectric response functions provide quantitative initial estimates of spectral ... |
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| Ground State Resonance Structure of Molecular Clusters of beta-HMX Calculated by Density Functional Theory for THz Frequencies |
21 JUN 2011 |
41 pages |
| Authors:
L. Huang; A. Shabaev; S. G. Lambrakos; L. Massa; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL MATERIALS SCIENCE
|
| We present calculations of ground state resonance structure associated with molecular clusters of HMX using density functional theory (DFT), which is for the construction of parameterized dielectric response functions for excitation by electromagnetic waves at compatible frequencies. These dielectric functions provide for different types of analyses concerning the dielectric response of explosives. In particular, these dielectric response functions provide quantitative initial estimates of spectral response features for subsequent adjustment with ... |
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| Ground State Resonance Structure of Some Typical High Explosives Calculated by Density Functional Theory |
04 Mar 2011 |
27 pages |
| Authors:
L Huang; A Shabaev; S G Lambrakos; N Bernstein; V Jacobs; D Finkenstadt; L Massa; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL MATERIALS SCIENCE
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| We present calculations of ground state resonance structure associated with the high explosives beta-HMX, PETN, RDX, TNT1 and TNT2 using density functional theory (DFT), which is for the construction of parameterized dielectric response functions for excitation by electromagnetic waves at compatible frequencies. These dielectric functions provide for different types of analyses concerning the dielectric response of explosives. In particular, these dielectric response functions provide quantitative initial estimates of spectral response ... |
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| Intrinsic Magnetism at Silicon Surfaces |
24 Aug 2010 |
7 pages |
| Authors:
Steven C Erwin; F J Himpsel; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL MATERIALS SCIENCE
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| It has been a long-standing goal to create magnetism in a non-magnetic material by manipulating its structure at the nanoscale. Many structural defects have unpaired spins; an ordered arrangement of these can create a magnetically ordered state. In this article we predict theoretically that stepped silicon surfaces stabilized by adsorbed gold achieve this state by self assembly, creating chains of polarized electron spins with atomically precise structural order. The spins ... |
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| Energetic, Vibrational and Electronic Properties of Silicon Using a Nonorthogonal Tight-Binding Model |
15 Aug 2000 |
12 pages |
| Authors:
N Bernstein; M J Mehl; D A Papaconstantopoulos; N I Papanicolaou; Martin Z Bazant; Efthimios Kaxiras; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL MATERIALS SCIENCE
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| We present calculations of energetic, electronic, and vibrational properties of silicon using a nonorthogonal tight-binding (TB) model derived to fit accurately first-principles calculations. Although it was fit only to a few high-symmetry bulk structures, the model can be successfully used to compute the energies and structures of a wide range of configurations. These include phonon frequencies at high-symmetry points, bulk point defects such as vacancies and interstitials, and surface reconstructions. ... |
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