439 research outputs found
Functional Derivative of the Zero Point Energy Functional from the Strong Interaction Limit of Density Functional Theory
We derive an explicit expression for the functional derivative of the
subleading term in the strong interaction limit expansion of the generalized
Levy--Lieb functional for the special case of two electrons in one dimension.
The expression is derived from the zero point energy (ZPE) functional, which is
valid if the quantum state reduces to strongly correlated electrons in the
strong coupling limit. The explicit expression is confirmed numerically and
respects the relevant sum-rule. We also show that the ZPE potential is able to
generate a bond mid-point peak for homo-nuclear dissociation and is properly of
purely kinetic origin. Unfortunately, the ZPE diverges for Coulomb systems,
whereas the exact peaks should be finite.Comment: 12 pages, 7 figure
Kohn-Sham equations with functionals from the strictly-correlated regime: Investigation with a spectral renormalization method
We re-adapt a spectral renormalization method, introduced in nonlinear
optics, to solve the Kohn-Sham (KS) equations of density functional theory
(DFT), with a focus on functionals based on the strictly-correlated electrons
(SCE) regime, which are particularly challenging to converge. Important aspects
of the method are: (i) the eigenvalues and the density are computed
simultaneously; (ii) it converges using randomized initial guesses; (iii) easy
to implement. Using this method we could converge for the first time the
Kohn-Sham equations with functionals that include the next leading term in the
strong-interaction limit of density functional theory, the so-called zero-point
energy (ZPE) functional as well as with an interaction-strength-interpolation
(ISI) functional that includes both the exact SCE and ZPE terms. This work is
the first building block for future studies on quantum systems confined in low
dimensions with different statistics and long-range repulsions, such as
localization properties of fermions and bosons with strong long-range repulsive
interactions in the presence of a random external potential
Fermionic statistics in the strongly correlated limit of Density Functional Theory
Exact pieces of information on the adiabatic connection integrand
, which allows to evaluate the exchange-correlation energy
of Kohn-Sham density functional theory, can be extracted from the leading terms
in the strong coupling limit (, where is the
strength of the electron-electron interaction). In this work, we first compare
the theoretical prediction for the two leading terms in the strong coupling
limit with data obtained via numerical implementation of the exact Levy
functional in the simple case of two electrons confined in one dimension,
confirming the asymptotic exactness of these two terms. We then carry out a
first study on the incorporation of the fermionic statistics at large coupling
, both numerical and theoretical, confirming that spin effects enter
at orders
Locating ship strike risk hotspots for fin whale (Balaenoptera physalus) and sperm whale (Physeter macrocephalus) along main shipping lanes in the North-Western Mediterranean Sea
Abstract The Pelagos Sanctuary is the only pelagic marine protected area in the Mediterranean Sea, instituted for the conservation of cetaceans. Considering the number and size of commercial and touristic ports located along its coasts, this protected area is highly impacted by human activities, and especially marine traffic. Fin whales and sperm whales are regularly sighted in the Pelagos Sanctuary, and ship strikes with large vessels are one of the main threats affecting these two species. Mapping hotspots of distribution along main shipping lanes could be an effective conservation tool, as they directly allow locating high risk areas. In this work, we used data collected during summer from 2009 to 2019, along main marine traffic corridors in the central region of Pelagos Sanctuary. Ship strike hotspots have been identified, considering the persistence of distribution hotspots over the 11 years period. Hotspots occurrence has then been predicted over the entire Pelagos Sanctuary area applying Generalized Additive Models, allowing for ship strike risk assessment over the marine protected area. Our results highlighted the recurrence of important areas for both species along shipping lanes characterized by high vessel traffic, identifying regions where to address conservation measures
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