1.

Norm squared of the PtPc molecule’s lowest π orbital (left), HOMO (middle) and LUMO (right) in a plane between the PtPc molecule and the buffer (at z = −1 Å). The symbols mark the underlying buffer lattice positions for the LiF (upper right), NaCl (lower right), KBr (lower left) and RbI (upper left) buffers, emphasizing the small number of RbI sites close to the molecule. The Pt atom is assumed to be adsorbed on top of a cation. The symbol “o” marks positions for which the buffer s and p _z orbitals do not couple to the PtPc MO for symmetry reasons, while “x” marks positions where coupling is possible. Because of the many nodal planes of the HOMO, it does not couple to s- and p _z -orbitals at sites with high symmetry relative to the HOMO. Due to the large lattice parameter of RbI, these sites are essentially outside the range of the molecule, while for LiF a few such sites are not.