4,000 reference data points of the methylenimmonium cation (CH 2 NH + 2 ) were taken from the database as described in reference 9. In brief, the electronic properties of these points were obtained by means of multireference configuration interaction method including single and double excitations approach -employing an active space of 6 electrons in 4 orbitals -in conjunction with the aug-cc-pVDZ basis set -i.e. MRCISD(6,4)/augcc-pVDZ.