While at AIMS, Kossi has shown that the Density Functional Theory (DFT) in the Kohn Sham formulation works on a lattice for integer particle numbers by computing self consistently the exact Kohn-Sham potential for the Hubbard Model. He also investigated the fundamental gap problem in DFT and has discovered that for a very asymmetric potential the Kohn-Sham gap can be larger than the real gap.

After AIMS, Kossi completed a Master’s degree in Condensed Matter Physics at ICTP-EAIFR in Rwanda where he got the best performer award. He is currently a PhD student in Physics at Gustave Eiffel University in Paris – France.