Atomic pseudopotentials for reproducing π-orbital electron behavior in sp 2 carbon atoms

Abstract : A pseudo-potential system for an sp 2 carbon atom is built and tested as a building block for various pseudo-hydrocarbon polyenes and polycyclic aromatic hydrocarbons. This pseudo-system has a central charge of Z = 1, it contains only one electron. It is employed in ab-initio calculations in which several physical characteristics including the orbital energies and first ionisation energy, as well as first excitation energy and UV spectra, are found to be well-reproduced by the pseudo-system. Remarkably, not only are the π excitation energies in good agreement with the reference calculations, but also transition densities and intensities, confirming that the virtual space obtained with the pseudo-potentials is of excellent quality. Finally, this approach is capable of reproducing the π electron systems of small or large, planar or near-planar hydrocarbons at low computational cost.