which shows the sites with accumulation (red surfaces) or depletion (blue surfaces) of electron density after the doping (electron density redistribution). Fig. shows the Δρ(r) function for all the systems (at the same isovalue) and the magnitude of the ECT term. After doping, the accumulation of electron density is located at the TM-P bonds, while the electron density depletion is located at the TM atom as a result of the hybridization of the metal orbitals during the bonding.