Stability of delocalized nonlinear vibrational modes in graphene lattice Dina U. Abdullina, Maria N. Semenova, Aleksander S. Semenov, Elena A. Korznikova and Sergey V. Dmitriev Eur. Phys. J. B, 92 11 (2019) 249 Published online: 11 November 2019 DOI: 10.1140/epjb/e2019-100436-y