83 research outputs found
Advising the Individual Investor: Comparing the Federal Regulation of Investment Advisers, Banks, and Broker-Dealers
Whether to Grant an Individual Chapter 11 Debtor an Early Discharge
This Article provides a framework for determining whether to grant an \u27early\u27 discharge to an individual chapter 11 debtor. An early discharge permits such a debtor to receive a discharge before making all payments under the confirmed plan. The Article analyzes the circumstances that warrant issuing such an early discharge, and what information ought to be included in the disclosure statement, plan, and notice of confirmation hearing. The Article concludes that an individual chapter 11 debtor may obtain a early discharge: (1) upon confirmation of a reorganization plan where the debtor has paid unsecured creditors before confirmation, or where necessary to keep important customers or to obtain financing to pay unsecured creditors, or (2) after plan confirmation but before plan payments are finished if the unsecured creditors have received the required distribution and the debtor no longer has sufficient income to meet living expenses and to make the required payments
Implementation and Validation of Constrained Density Functional Theory Forces in the CP2K Package
Constrained density functional theory (CDFT) is a powerful tool for the prediction of electron transfer parameters in condensed phase simulations at a reasonable computational cost. In this work we present an extension to CDFT in the popular mixed Gaussian/plane wave electronic structure package CP2K, implementing the additional force terms arising from a constraint based on Hirshfeld charge partitioning. This improves upon the existing Becke partitioning scheme, which is prone to give unphysical atomic charges. We verify this implementation for a variety of systems: electron transfer in (H_{2}O)_{2}^{+} in a vacuum, electron tunnelling between oxygen vacancy centers in solid MgO, and electron self-exchange in aqueous Ru^{2+}-Ru^{3+}. We find good agreement with previous plane-wave CDFT results for the same systems, but at a significantly lower computational cost, and we discuss the general reliability of condensed phase CDFT calculations
Origin of the large phonon band-gap in SrTiO3 and the vibrational signatures of ferroelectricity in ATiO3 perovskite: First principles lattice dynamics and inelastic neutron scattering of PbTiO3, BaTiO3 and SrTiO3
We report first principles density functional perturbation theory
calculations and inelastic neutron scattering measurements of the phonon
density of states, dispersion relations and electromechanical response of
PbTiO3, BaTiO3 and SrTiO3. The phonon density-of-states of the quantum
paraelectric SrTiO3 is found to be fundamentally distinct from that of
ferroelectric PbTiO3 and BaTiO3 with a large 70-90 meV phonon band-gap. The
phonon dispersion and electromechanical response of PbTiO3 reveal giant
anisotropies. The interplay of covalent bonding and ferroelectricity, strongly
modulates the electromechanical response and give rise to spectacular
signatures in the phonon spectra. The computed charge densities have been used
to study the bonding in these perovskites. Distinct bonding characteristics in
the ferroelectric and paraelectric phases give rise to spectacular vibrational
signatures. While a large phonon band-gap in ATiO3 perovskites seems a
characteristic of quantum paraelectrics, anisotropy of the phonon spectra
correlates well with ferroelectric strength. These correlations between the
phonon spectra and ferroelectricity, can guide future efforts at custom
designing still more effective piezoelectrics for applications. These results
suggest that vibrational spectroscopy can help design novel materials.Comment: 11 pages, 4 color figures and 2 Table
Dual strain mechanisms in a lead-free morphotropic phase boundary ferroelectric
Electromechanical properties such as d33 and strain are significantly enhanced at morphotropic phase
boundaries (MPBs) between two or more different crystal structures. Many actuators, sensors and
MEMS devices are therefore systems with MPBs, usually between polar phases in lead (Pb)-based
ferroelectric ceramics. In the search for Pb-free alternatives, systems with MPBs between polar
and non-polar phases have recently been theorized as having great promise. While such an MPB
was identified in rare-earth (RE) modified bismuth ferrite (BFO) thin films, synthesis challenges
have prevented its realization in ceramics. Overcoming these, we demonstrate a comparable
electromechanical response to Pb-based materials at the polar-to-non-polar MPB in Sm modified
BFO. This arises from ‘dual’ strain mechanisms: ferroelectric/ferroelastic switching and a previously
unreported electric-field induced transition of an anti-polar intermediate phase. We show that
intermediate phases play an important role in the macroscopic strain response, and may have potential
to enhance electromechanical properties at polar-to-non-polar MPBs
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