Category Archives: research

Luminescence of hexagonal boron nitride explained

Luminescence of hexagonal boron nitride (hBN) has puzzled researchers for long time. In standard solid state physics textbooks direct band gap semiconductors are considered efficient light emitters while indirect ones are regarded as inefficient. Hexagonal boron nitride seems to defy this rule. In fact hBN emits light in the ultraviolet with an efficient comparable to… Read More

Direct and indirect excitons in boron nitride polymorphs: a story of atomic configurations and electronic correlation

In this work we study how different atomic configurations, and electronic correlation modify the exciton dispersion in hexagonal boron nitride. We use two different approaches, ab-initio DFT plus many-body perturbation theory and tight-binding. We found that in the case of AB-stacking electronic correlation inverts the nature of the optical gap, from indirect to direct respect… Read More

OPTEL2D: Opto-electronic properties of 2D Transition Metal Dichalcogenides with DFT and post-DFT simulations

Our Prace research project OPTEL2D “Opto-electronic properties of 2D Transition Metal Dichalcogenides with DFT and post-DFT simulations” has been accepted, and we got 49.5 million core hours on Marconi – KNL.     Here the project description: “Two-dimensional (2D) and layered materials possess novel combinations of electronic and optical properties and thus present a unique… Read More

Two-photon absorption in two-dimensional crystals

In this work we combine tight-binding calculations of the two-photon transition probability with sophisticated ab-initio real-time Bethe-Salpeter simulations of the two-photon resonance third-order susceptibility. This combination is a unique feature of this work: on the one hand the tight-binding calculations allow us to identify the symmetry properties of the excitons, on the other hand the… Read More

Invisible excitons in hexagonal Boron Nitride

New talk for the conference “2D layered materials for opto-electronics: a theoretical/computational perspective” in Rome. In this work we study excitations in hexagonal Boron Nitride that are invisible in linear optical response. We show that these dark states can be measured with other spectroscopic techniques and they play an important roles in the luminescence response… Read More

Exciton interference in hexagonal boron nitride

Our new paper on exciton interference in hexagonal boron nitride is online. In this paper we show  that the excitonic peak  at finite momentum is formed by the superposition of two groups of transitions that we call KM and MK′ from the k-points involved in the transitions. These two groups contribute to the peak intensity… Read More

New talks at the 2017 ETSF conference in Frascati

Here my new two talks at the 2017 ETSF conference in Franscati. The first on Scientific Publishing and the SciPost journal where I will discuss the actual situation of the scientific publishing system and how new green open access journal, like SciPost, could change it. The second talk on the Lumen code, an ab-initio code… Read More

Phd Position at SIMaP

Computational study of MOFs for an efficient carbon capture Applications are invited for a fully funded 3-years PhD position to work on the electronic structure modeling of porous coordination polymers starting on October 1st 2017 and funded by the ANR ComputationalCarbonCapture. We propose to design novel families of MOFs whose high affinity for CO2 can… Read More

Modeling excitons in bulk and single-layer hBN

New paper on excitations in hexagonal Boron-Nitride. Core and low energy electronic excitations have been studied in hexagonal boron nitride by means of angular resolved electron energy loss spectroscopy and theoretical calculations. Paper: Angular resolved electron energy loss spectroscopy in hexagonal boron nitride Poster: Modeling excitons in bulk and single-layer hBN

What is the nature of the C-C complex in silicon? Insights from electronic structure calculations

In this work we studied the C-C defect complex in silicon. We used different approaches in such a way to identity the defect configuration responsible for the strong light emission in irradiated silicon. Our clues point towards a particular configuration, even if we suspect that in a damaged sample different type of complexes could be… Read More