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
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 .
The second general meeting of the GDR-REST will be held in the Porquerolles island from 22.05. to 25.05.2018. This meeting aims to bring together different communities of theoretical spectroscopy which are/were historically separated, but unified under a very precise and important subject: the excited-states spectroscopy of variety of systems (for both weakly and strongly correlated… Read More
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
Here I show how to calculate GW correction for a generic k-point not included in the original grid used to perform a GW calculations using Yambo 4.2. This method allows to obtain the GW correction without the need of recalculate the full dielectric constant used in the initial calculation. As example I will take 2-dimensional… Read More
Convergence of dielectric constant with respect the number of k-points can be very slow in many systems. For this reason in Yambo it is implemented a double-grid technique that speeds up convergence versus k-points with a computational cost comparable to the standard calculations. The method is described in the paper: Speeding up the solution of… Read More
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
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
A new version of the Lumen code is available online. It includes spin-orbit coupling, the possibility to use polarised light and the real-time Bethe-Salpeter equation (RT-BSE). Notice that the RT-BSE is limited to small systems or a small number of G-vectors in the screened-exchange due to its computational time. New tutorials on spin-orbit coupling and… Read More
At CINaM together with Andres Saul and Hans-christian Weissker we are organizing a series of lectures on DFT and the Quantum Espresso code. The course will cover standard DFT, functionals, psedo-potentials, surfaces, STM images, structure optimization, etc.. Teaching material and lecture notes can be downloaded here: DFT and Quantum Espresso 1 DFT and Quantum Espresso… Read More