Dr. Florent Tournus

During my PhD, in Lyon (France), I have studied different cases of doping in covalent cage-like nanostructured materials. I have studied experimentally (by Raman spectroscopy, X-ray absoprtion and X-ray diffraction) and theoretically (ab initio simulations in the density functional theory formalism with the SIESTA code that uses a localized basis set) some materials made of covalent cages: C60 and silicon clathrates. Thus, my scientific background does not only concern ab initio calculations and my postdoctoral position at the PCPM is a good opportunity to have further training in this field.

My work in the Exciting network, where I work with X. Gonze and Y. Pouillon, is related to the milestone M6 (comparison of different approaches), and also to the milestones M5, M2 and M1. More precisely, I determine energy surfaces of ground state and excited states for the dissociation of diatomic molecules, using the SCF method. This allows a comparison with the results of the excitations obtained from time dependent density functional theory (TD-DFT). This study is useful to get a better understanding of the present results obtained for the ground state dissociation of molecules calculated within the adiabatic connection fluctuation-dissipation (ACFD) framework. This formalism should be able to account correctly for van der Waals interactions, at all distances.

The calculations are performed with the ABINIT code, which uses a plane wave basis set. This postdoctoral position is the occasion for me to get more familiar with this formalism. I have also enhanced my knowledge of the physics of excited electronic states and of the different actual methods used in the calculations. It is a great opportunity to work in a European network and I find that it is a very positive experience, from a human an scientific point of view.