10,671 research outputs found
Self-dual formulations of d=3 gravity theories in the path-integral framework
We study the connection, at the quantum level, between d=2+1 dimensional
self-dual models with actions of growing (from first to fourth) order,
governing the dynamics of helicity +2 (or -2) massive excitations. We obtain
identities between generating functionals of the different models using the
path-integral framework, this allowing to establish dual maps among relevant
vacuum expectation values. We check consistency of these v.e.v.'s with the
gauge invariance gained in each mapping.Comment: 26 pages. LaTeX. Minor changes. Published in Int. J Modern Phys. A;
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Joint Density-Functional Theory of the Electrode-Electrolyte Interface: Application to Fixed Electrode Potentials, Interfacial Capacitances, and Potentials of Zero Charge
This work explores the use of joint density-functional theory, a new form of
density-functional theory for the ab initio description of electronic systems
in thermodynamic equilibrium with a liquid environment, to describe
electrochemical systems. After reviewing the physics of the underlying
fundamental electrochemical concepts, we identify the mapping between commonly
measured electrochemical observables and microscopically computable quantities
within an, in principle, exact theoretical framework. We then introduce a
simple, computationally efficient approximate functional which we find to be
quite successful in capturing a priori basic electrochemical phenomena,
including the capacitive Stern and diffusive Gouy-Chapman regions in the
electrochemical double layer, quantitative values for interfacial capacitance,
and electrochemical potentials of zero charge for a series of metals. We
explore surface charging with applied potential and are able to place our ab
initio results directly on the scale associated with the Standard Hydrogen
Electrode (SHE). Finally, we provide explicit details for implementation within
standard density-functional theory software packages at negligible
computational cost over standard calculations carried out within vacuum
environments.Comment: 18 pages, 5 figures. Initially presented at APS March Meeting 2010.
Accepted for publication in Physical Review B on Jul. 27, 201
Robust ab initio calculation of condensed matter: transparent convergence through semicardinal multiresolution analysis
We present the first wavelet-based all-electron density-functional
calculations to include gradient corrections and the first in a solid. Direct
comparison shows this approach to be unique in providing systematic
``transparent'' convergence, convergence with a priori prediction of errors, to
beyond chemical (millihartree) accuracy. The method is ideal for exploration of
materials under novel conditions where there is little experience with how
traditional methods perform and for the development and use of chemically
accurate density functionals, which demand reliable access to such precision.Comment: 4 pages, 3 figures, 4 tables. Submitted to Phys. Rev. Lett. (updated
to include GGA
Quantum Phase Transitions in the Interacting Boson Model: Integrability, level repulsion and level crossing
We study the quantum phase transition mechanisms that arise in the
Interacting Boson Model. We show that the second-order nature of the phase
transition from U(5) to O(6) may be attributed to quantum integrability,
whereas all the first-order phase transitions of the model are due to level
repulsion with one singular point of level crossing. We propose a model
Hamiltonian with a true first-order phase transition for finite systems due to
level crossings.Comment: Accepted in PR
A computationally efficacious free-energy functional for studies of inhomogeneous liquid water
We present an accurate equation of state for water based on a simple
microscopic Hamiltonian, with only four parameters that are well-constrained by
bulk experimental data. With one additional parameter for the range of
interaction, this model yields a computationally efficient free-energy
functional for inhomogeneous water which captures short-ranged correlations,
cavitation energies and, with suitable long-range corrections, the non-linear
dielectric response of water, making it an excellent candidate for studies of
mesoscale water and for use in ab initio solvation methods.Comment: 6 pages, 5 figure
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