Flowchart illustrating how the stability of normal modes depends on the decay constant \(\gamma\) and the damping frequency \(\delta\). In general, stable states can be only be reached for positive decay constants, i.e. in damped systems. If, for \(\gamma>0\), the damping frequency is real, the system is in the stable underdamped state; if \(\delta\) equals zero, the system is critically damped. For imaginary damping frequencies, the system is overdamped; here, its stability depends on the sign of both the difference and sum of \(\gamma\) and \(\delta\).