The JT distortion of small molecules (or molecular ions) is directly deduced from electronic structure calculations of their APES (through DFT and/or ab initio computations). These molecules / ions are often radicals, such as trimers of alkali atoms (Li 3 and Na 3), that have unpaired spins and in particular in (but not restricted to) doublet states. Besides the JTE in E′ and E″ states, also the pseudo JTE between an E state and a nearby A state may play a role. The JT distortion reduces the symmetry from D 3h to C 2v (see figure), and it depends on the details of the interactions whether the isosceles triangle has an acute or an obtuse-angled (such as Na 3) minimum energy structure. Natural extensions are systems like NO 3 and NH 3 where a JT distortion has been documented in the literature for ground or excited electronic states.