All-optical seeding of a light-induced phase transition with correlated disorder

Ultrafast manipulation of vibrational coherence is an emergent route to control the structure of solids. However, this strategy can only induce long-range correlations and cannot modify atomic structure locally, which is required in many technologically-relevant phase transitions. Here, we demonstrate that ultrafast lasers can generate incoherent structural fluctuations which are more efficient for material control than coherent vibrations, extending optical control to a wider range of materials. We observe that local, non-equilibrium lattice distortions generated by a weak laser pulse reduce the energy barrier to switch between insulating and metallic states in vanadium dioxide by 6%. Seeding inhomogeneous structural-fluctuations presents an alternative, more energy efficient, route for controlling materials that may be applicable to all solids, including those used in data and energy storage devices

Local Description with Lewis Structures at the Hückel Level

International audienceThe chapter describes two approaches that aim at a semi-empirical description of Lewis structures and their interaction, within the Hückel method framework. They have been embedded in the HuLiS program, which is freely available since 2008. Two methods are described and discussed here. They are based either on a dressed Configuration Interaction (CI) hamiltonian matrix, called Hückel-Lewis-CI (HL-CI), or on an overlap-based approach, called the Hückel-Lewis-Projection method (HL-P)

Arsenic 2D a New Anode Material for Rechargeable Batteries: First Principal Calculation

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