395 research outputs found

    Along strike preorogenic thickness variation and onlapping geometries control on thrust wedge evolution: insight from sandbox analogue modelling

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    Abstract: Thickness variation of sedimentary sequences is largely viewed as a controlling factor on the evolution of orogenic wedges; among the different structural and stratigraphic features generating thickness variation, we focused our analysis on the onlapping geometries, using laboratory sandbox experiments. The aim was trying to describe how a common sedimentary configuration could influence thrusts geometry and mode of accretion. Model results showed that onlapping geometries in pretectonic sediments cause a great complexity, dominated by curvilinear thrusts, back thrust and out-ofsequence thrusts. They also influence mode of accretion, generating diachronous thrusting along strike, reactivation and under-thrusting alternating to simple piggy-back sequence. Our modeling results are compared with natural examples from the Apennines, the southern Pyrenees, the Pindos (Greece) and the West Spitsbergen (Greenland) fold and thrust belts, among many others, where strain localization and diachronic thrusting affecting thrust propagation in correspondence to complex geometries both in the pre-orogenic stratigraphy and in the upper crust

    A Combined Periodic Density Functional and Incremental Wave-Function-Based Approach for the Dipersion-Accounting Time-Resolved Dynamics of 4He Nanodroplets on Surfaces: 4He/Graphene

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    Helium-mediated Synthesis, Soft-landing and Spectroscopy of Metal Nanoparticles on Surfaces,CSIC, Madrid, Spain, October 10-11, 2014A general strategy to calculate accurate He-surface interaction potentials is proposed [1]. It extends the dispersionless density functional (dlDF) approach by Pernal et al. [2] to adsorbatesurface interactions by including periodic boundary conditions [1b]. A scheme to parametrize the dispersion interaction is introducced by calculating two- and three-body dispersion terms at CCSD(T) level via the method of increments [3]. The performance of the composite approach is tested on the low-lying selective adsorption states of 4He/graphene [5]. Second, its capability to describe dispersionless correlation effects realistically is used to extract dispersion effects in time-dependent density functional simulations on the collision of 4He droplets with graphene [1b]. Dispersion effects play a key role in the fast spreading of the 4He nanodroplet [1b,6], the evaporation-like process of helium atoms, and the formation of solid-like helium structures. These characteristics are expected to be quite general and highly relevant to explain experimental measurements with the newly developed helium droplet mediated deposition technique [7].Peer Reviewe

    Combining the Hybrid Functional Method with Dynamical Mean-Field Theory

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    We present a new method to compute the electronic structure of correlated materials combining the hybrid functional method with the dynamical mean-field theory. As a test example of the method we study cerium sesquioxide, a strongly correlated Mott-band insulator. The hybrid functional part improves the magnitude of the pd-band gap which is underestimated in the standard approximations to density functional theory while the dynamical mean-field theory part splits the 4f-electron spectra into a lower and an upper Hubbard band.Comment: 5 pages, 2 figures, replaced with revised version, published in Europhys. Let

    Reversible, Opto-Mechanically Induced Spin-Switching in a Nanoribbon-Spiropyran Hybrid Material

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    It has recently been shown that electronic transport in zigzag graphene nanoribbons becomes spin-polarized upon application of an electric field across the nanoribbon width. However, the electric fields required to experimentally induce this magnetic state are typically large and difficult to apply in practice. Here, using both first-principles density functional theory (DFT) and time-dependent DFT, we show that a new spiropyran-based, mechanochromic polymer noncovalently deposited on a nanoribbon can collectively function as a dual opto-mechanical switch for modulating its own spin-polarization. These calculations demonstrate that upon mechanical stress or photoabsorption, the spiropyran chromophore isomerizes from a closed-configuration ground-state to a zwitterionic excited-state, resulting in a large change in dipole moment that alters the electrostatic environment of the nanoribbon. We show that the electronic spin-distribution in the nanoribbon-spiropyran hybrid material can be reversibly modulated via noninvasive optical and mechanical stimuli without the need for large external electric fields. Our results suggest that the reversible spintronic properties inherent to the nanoribbon-spiropyran material allow the possibility of using this hybrid structure as a resettable, molecular-logic quantum sensor where opto-mechanical stimuli are used as inputs and the spin-polarized current induced in the nanoribbon substrate is the measured output.Comment: Accepted by Nanoscal
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