Non-empirical calculation of electronic states of impurity polygon in carbon sheet: 1, 2 and 3 pentagons

Electronic states of 1, 2 and 3 impurity pentagons in carbon sheet are calculated by the DV-Xα-LCAO method. The C atoms near the tail end are negatively charged and other C atoms are almost neutral. Both the occupied and unoccupied orbitals near the HOMO have high charge density around the central pentagon and tail end. This well reproduces the scanning tunneling microscopy images of 1 impurity pentagon. Furthermore, electronic states of 2 and 3 impurity pentagons in carbon sheet resemble those of fullerene molecule C60 adsorbed on Si(0 0 1)2×1 and Si(1 1 1)7×7 surfaces, respectively.