Bienvenue - Laboratoire Jacques-Louis Lions

Organisateur : Pierre Monmarché
Lieu : sauf mention contraire, soit au LJLL (tours 15-16, salle 309), soit à la bibliothèque du LCT (tours 12-13, 4ème étage).

Prochaines sessions et événements

• Vendredi 07/06/2019 à 15h30 au LJLL, Israel Michael Sigal (University of Toronto), On effective equations of quantum physics.
  Abstract : The Hartree-Fock (HF) equation is a (if not the) key effective equation of quantum physics. It was discovered by Bardeen, Cooper and Schrieffer for fermions and by Bogolubov, for bosons, that for quantum fluids (superconductors and superfluids, respectively) :
   the HFE falls short
   there is a generalization of the HFE describing these phenomena.
  It turns out that this generalization is mathematically very natural and leads to the (time-dependent) Bogolubov-de Gennes (BdG) or Hartree-Fock-Bogolubov (HFB) equations, depending on whether we deal with fermions or bosons. (The former give an equivalent formulation of the BCS theory of superconductivity while the latter describe superfluids and the BE condensation.)
  There are many fundamental open problems about these equations. In this talk, I will explain how these equations emerge from the N-body Schrödinger equations, will discuss their general features and key physical classes of stationary solutions and review some recent results.
  The talk is based on joint work with Ilias Chenn and with V. Bach, S. Breteaux, Th. Chen and J. Fröhlich.

• Vendredi 14/06/2019 à 15h30 au LJLL, Gabriel Stoltz (CERMICS, ENPC), Hybrid Monte Carlo methods for sampling probability measures on submanifolds.
  Abstract : The aim of this talk is to provide a gentle introduction to sampling molecular systems with constraints. Constraints can be considered in molecular dynamics as a way to either take care of very stiff degrees of freedom, or to compute properties of interest such as free energies. From a mathematical viewpoint, the aim is to sample probability measures supported on submanifolds. This can be done using standard discretization schemes of stochastic differential equations such as Langevin or overdamped Langevin dynamics, adapted to the situation when the dynamics is constrained to remain on a submanifold. In order to avoid discretization biases related to the finiteness of the timestep, a Metropolis acceptance/rejection procedure can be superimposed. The so-obtained scheme belongs to the class of generalized Hybrid Monte Carlo (GHMC) algorithms. Some care however has to be taken in order to obtain a fully reversible method since the projection onto the submanifold of interest may not be well defined. I will provide elements of mathematical analysis to this end, as well as illustrative numerical experiments — as well as tracks for further investigations on actual molecular systems.

Événements et sessions passés

• Vendredi 24/05/2019 à 15h30 au LJLL, Jeremy Dalphin (Sorbonne Université), On the Computation of Maximal Probability Domains (MPDs) in Quantum Chemistry.

• Vendredi 10/05/2019 à 15h30 au LCT, Federica Agostini (LCP, Université Paris-Sud), Dynamics of electrons and nuclei in molecules : Beyond the Born-Oppenheimer approximation

• Vendredi 19/04/2019 à 15h30 au LJLL, Éric Cancès (ENPC), seconde session sur l’informatique quantique.

• Vendredi 05/04/2019 à 15h30 au LCT, Martin Weigt (LCQB, Sorbonne Université) Data-driven models of protein sequence landscapes : inference, 3D structure prediction and protein design

• Vendredi 22/03/2019 à 15h30 au LCT, Simon Huppert (INSP, Sorbonne Université) Utilisation du bain thermique quantique pour la simulation des effets quantiques nucléaires.

• Vendredi 08/03/2019 à 15h30 au LCT, David Perahia (ENS Paris-Saclay) et Mauricio Costa (Fondation Oswaldo-Cruz) : Exploration étendue des conformations des macromolécules biologiques par excitation cinétique des modes normaux de basse fréquence.

• Vendredi 22/02/2019 Éric Cancès (ENPC) : An elementary introduction to quantum entanglement and its applications in physics and quantum computer science (présentation (pdf))

• Vendredi 15/02/2019 Jérôme Hénin (IBPC, Sorbonne Université) : Collective variable biases : a toolbox for computational experiments in biology

• Vendredi 18/01/2019 Anatole von Lilienfeld (Universität Baesel) : Quantum Machine Learning

• Mardi 18/12/2018 Shiang Fang (Harvard University) : Ab initio Electronic Structure Modeling of Layered Material Stacks

• Vendredi 30/11/2018 Upanshu Sharma (Cermics) : Quantifying coarse-graining error in SDEs.

• Vendredi 23/11/2018 Michael Herbst (Heidelberg University) : Design of the molsturm quantum-chemistry framework. (abstract)

• Vendredi 09/11/2018, Louis Thiry (ENS Paris) : Solid harmonic scattering transform for quantum energy regression (présentation (pdf))

• Vendredi 26/10/2018 Riccardo Spezia (LCT) : Molecular reaction dynamics. Quasi-classical trajectories and beyond. (abstract, présentation (pptx))

• 9-10-11 janvier 2017 : Journées GDR Correl