J.H. Los, R.C. Ouwersloot, A. Fasolino, M.I. Katsnelson, Theory of Condensed Matter, Institute of Molecules and Materials, Radboud University, Nijmegen, The Netherlands  As recently explicitly demonstrated by simulation [1], the elastic properties of pristine graphene depend on the system size as a power law. For example, for a system of 1 cm^2, the in-plane elastic constants are about 100 times (!) smaller while the out-of-plane elastic constant, i.e. the bending rigidity, is about 10000 times (!!) largerthan for a system of nanometer size. This anomalous behavior, rooted in the theory of membranes, originates from the strong anharmonic coupling between large out-of-plane modes and in-plane modes. This coupling is in fact what stabilizes graphene as a relatively flat phase. Considering graphene with defects, such as single vacancies,or polycrystalline graphene, other length scales come into play. This not only affects the bare elastic properties but also their size dependence. I will give an overview of the situation regarding the scaling behavior of the elastic properties of defected graphene systems, providing amongst others an explanation for the recently, experimentally observed strong increase of the Young modulus of graphene with a low density of single vacancies [2]. [1] J.H. Los, A. Fasolino, and M. I. Katsnelson, Phys. Rev. Lett. 116, 015901 (2016). [2] G. Lopez-Polin, C. Gomez-Navarro, V. Parente, F. Guinea, M. I. Katsnelson, F. Perez-Murano, and Julio Gomez-Herrero, Nature Physics, 26-31 (2015).  After my PhD in the theory of condensed matter group at the Radboud University in Nijmegen (Netherlands), and having worked as a researcher in different locations in Europe on various topics in the field of theory of condensed matter, modelling and simulation, I am now back in the group where I did my PhD. My current research activities concentrate on graphene/2D systems, their (statistical-)mechanical properties, development of effective interatomic interaction models enabling large scale simulation. |