Modulational instability and travelling waves in (2+1)-dimensional alpha-helix protein chains with diagonal and off-diagonal couplingsR. Y. Ondoua, J. C. Mimshe Fewu, Salathiel Yakada, C. B. Tabi and H. P. Ekobena FoudaEur. Phys. J. Plus, 139 6 (2024) 514DOI: https://doi.org/10.1140/epjp/s13360-024-05321-w