2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/168776Group theoretical arguments combined with normal mode analysis techniques are applied to a coarse-grained approximation of icosahedral viral capsids which incorporates areas of variable flexibility. This highlights a remarkable structure of the low-frequency spectrum in this approximation, namely the existence of a plateau of 24 near zero-modes with universal group theory content.5 pages, 4 figures; v2: improved presentation, version published in Phys. Rev. EBiomoleculestext