Figure 3. Calculated minimum energy path between the localized and delocalized state of the DMP cation.

The energy of images, E_img, in the nudged elastic band calculations is given with respect to the energy of the localized state, E_1, as a function of the accumulated displacement of the atoms, ΔR. The red dots show results of a PZ-SIC calculation where a barrier of 0.2 eV separates the metastable, localized state from the delocalized state. The green dots show results of calculations using the M06-HF functional where MP2 optimized structures are used for the end points. In the M06-HF calculations, the energy barrier is not present and a structure optimization starting from the localized state converges on the delocalized state. Similar results were obtained for all other commonly used DFT functionals.