Extreme values of elastic strain and energy in sine-Gordon multi-kink collisionsAliakbar Moradi Marjaneh, Alidad Askari, Danial Saadatmand and Sergey V. DmitrievEur. Phys. J. B, 91 1 (2018) 22DOI: https://doi.org/10.1140/epjb/e2017-80406-y