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Accueil du site > Séminaires > Séminaires 2010 > From Time-Dependent Current-Density Functional Theory to Many-Body Perturbation Theory : (non)linear response of models, molecules, and solids

mercredi 10 février - 14H00, attention horaire exceptionnel

From Time-Dependent Current-Density Functional Theory to Many-Body Perturbation Theory : (non)linear response of models, molecules, and solids

Pina Romaniello (LSI, Polytechnique)

par Pierre Pujol - 10 février 2010

In this talk I will give an overview of my scientific work, which covers the following research lines : i) study of the linear and nonlinear response of molecules using Time-Dependent Density-Functional Theory (TDDFT) [1] ; ii) formulation, implementation, and application of the linear response of metals within (relativistic)TD Current-DFT, where the basic quantity is the current density of the system, instead of the density as in TDDFT [2] ; iii) theory development in (TD)DFT using Many-Body Perturbation Theory (MBPT)[3,4], where one needs to approximate the self-energy, which plays a similar role as the exchange-correlation potential in a density-functional context. Passing through MBPT has the advantage that approximations with a clear physical meaning can be more easily designed than in the context of density functionals, and introduce in a second step in the more efficient (TD)DFT. I will in particular focus on this last point, and I will illustrate how one can exploit the link TDDFT<->MBPT, which is mainly used for linear-response TDDFT, to find better approximations in real time TDDFT. The latter formulation allows one to treat any dynamical regime, from linear to highly nonlinear effects.

[1] P. Romaniello and F. Lelj, Chem. Phys. Lett. 372, 51 (2003) ; T. Cassano, R. Tommasi, L. Nitti, M. C. Aragoni, M. Arca, C. Denotti , F. A. Devillanova, F. Isaia, V. Lippolis, F. Lelj, and P. Romaniello, J. Chem. Phys. 118, 5995 (2003).

[2] P. Romaniello and P. L. de Boeij, Phys. Rev. B 71, 155108 (2005) ; J. Chem. Phys. 122, 164303 (2005) ; J. Chem. Phys. 127, 174111, (2007).

[3] L. Hedin, Phys. Rev. 139, A796 (1965).

[4] P. Romaniello, D. Sangalli, J. A. Berger, F. Sottile, L. Molinari, L. Reining, G. Onida, J. Chem. Phys. 130, 044108, (2009).