RT journal article T1 From Stability to Chaos: A Complete Classification of the Damped Klein-Gordon Dynamics A1 Lizama, Carlos A1 Murillo Arcila, Marina A1 Puerta Fernández, Julio A2 Matemáticas K1 C0-semigroups K1 Devaney chaos K1 Herzog spaces K1 Klein-Gordon equation K1 stability AB We investigate the transition between stability and chaos in the damped Klein-Gordon equation, a fundamental model for wave propagation and energy dissipation. Using semigroup methods and spectral criteria, we derive explicit thresholds that determine when the system exhibits asymptotic stability and when it displays strong chaotic dynamics, including Devaney and distributional chaos as well as topological mixing. The results yield a classification of the dynamical regimes in terms of damping, stiffness, and propagation parameters, showing that the system admits only two long-term behaviours: convergence to equilibrium or chaos. This dichotomy not only unifies and extends previous partial results but also highlights the mechanisms by which linear partial differential equations can generate complex dynamics typically associated with nonlinear systems. Potential applications arise in acoustics, wave mechanics, and signal transmission, where predicting the onset of chaos versus stability is of practical importance. PB John Wiley and Sons Ltd SN 1099-1476 YR 2026 FD 2026 LK http://hdl.handle.net/10498/38667 UL http://hdl.handle.net/10498/38667 LA eng DS Repositorio Institucional de la Universidad de Cádiz RD 10-nov-2026