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Find video protocols related to scientific articles indexed in Pubmed.
Transport in tight-binding bond percolation models.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 09-19-2014
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Most of the investigations to date on tight-binding, quantum percolation models focused on the quantum percolation threshold, i.e., the analog to the Anderson transition. It appears to occur if roughly 30% of the hopping terms are actually present. Thus, models in the delocalized regime may still be substantially disordered, hence analyzing their transport properties is a nontrivial task which we pursue in the paper at hand. Using a method based on quantum typicality to numerically perform linear response theory we find that conductivity and mean free paths are in good accord with results from very simple heuristic considerations. Furthermore we find that depending on the percentage of actually present hopping terms, the transport properties may or may not be described by a Drude model. An investigation of the Einstein relation is also presented.
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Effect of short-range order on transport in one-particle tight-binding models.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 06-28-2013
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We investigate transport properties of topologically disordered three-dimensional one-particle tight-binding models, featuring site-distance-dependent hopping terms. We start from entirely disordered systems into which we gradually introduce some short-range order by numerically performing a pertinent structural relaxation using local site-pair interactions. Transport properties of the resulting models within the delocalized regime are analyzed numerically using linear response theory. We find that even though the generated order is very short ranged, transport properties such as conductivity or mean free path scale significantly with the degree of order. Mean free paths may exceed the site-pair correlation length. It is furthermore demonstrated that while the totally disordered model is not in accord with a Drude- or Boltzmann-type description, moderate degrees of order suffice to render such a picture valid.
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Transport in topologically disordered one-particle, tight-binding models.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 03-01-2013
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We aim at quantitatively determining transport parameters like conductivity, mean free path, etc., for simple models of spatially completely disordered quantum systems, comparable to the systems which are sometimes referred to as Lifshitz models. While some low-energy eigenstates in such models always show Anderson localization, we focus on models for which most states of the full spectrum are delocalized, i.e., on the metallic regime. For the latter we determine transport parameters in the limit of high temperatures and low fillings using linear response theory. The Einstein relation (proportionality of conductivity and diffusion coefficient) is addressed numerically and analytically and found to hold. Furthermore, we find the transport behavior for some models to be in accord with a Boltzmann equation, i.e., rather long mean free paths, exponentially decaying currents, while this does not apply to other models even though they are also almost completely delocalized.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.