Category Archives: non linear optics

How strong is the Second Harmonic Generation in single-layer monochalcogenides?

Single-layer monochalcogenides have recently attracted much attention in the scientific community for their strong non-linear response, in particular the second harmonic generation(SHG). The origin of this strong response is still debated. A strong mismatch exist between theory and experiments. In order to clarify this issue, in this work we performed first-principles calculation of linear and… Read More

Theoretical Spectroscopy Lectures

This year I was invited to give two lectures at the school on “Theoretical Spectroscopy” organized by F. Sottile, V. Olevano and G. Rignanese. I will present two lectures on “Non-linear approaches to TDDFT :: non perturbative real-time” and “Bethe-Salpeter Equation in real time” and a tutorial on the Lumen code. All the lectures are… 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

Role of excitonic effects in nonlinear optical properties of 2D materials

My collaborator Myrta Grüning gave a very interesting talk about the role of excitons in non-linear optical properties of 2D materials at the OSI 2017 conference. She discusses  both second and third harmonic generation in low dimensional nanostructures. Slides of her talk are available here .

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

My thesis for the Habilitation à Diriger des Recherches

The first draft of my  thesis for the accreditation to direct research (Habilitation à Diriger des Recherches) is available online. The thesis covers my studies of the non-linear response in solids and nanostructures by means of real-time simulations.  In the thesis I discuss how to couple electrons and external fields by means of Modern Theory… Read More

Density Functional Polarization Theory

We present a new paper on Density Functional Polarization Theory (DFPT). This theory is an extension of Time-Dependent-DFT where the exchange correlation functional depends not only from the density but also from the polarization P. Thanks to this explicit dependence on P it is possible  solve different problems of TD-DFT in periodic systems with a… Read More

Nonlinear response of solids within the GW plus Bethe-Salpeter approximation

My new talk for the GDR-Corr is available online. In this talk I will present our new (probably not so new now) approach to calculate non-linear response in extended systems within the GW plus Bethe-Salpeter equation. I  put different references in the presentation that can be interesting for the reader.

Strong second harmonic generation in SiC, ZnO, GaN two-dimensional hexagonal crystals from first-principles many-body calculations

We published a new paper on the second harmonic generation(SHG) in two-dimensional hexagonal crystals SiC, ZnO and GaN. The SHG is calculated within the so called GW plus Bethe-Salpter formalism, using a real-time implementation proposed by some of us. We found that these system present a large region with a strong SHG before the absorption… Read More