  In order to study a magnetic principle of carbon based materials, multiple
spin state of zigzag edge modified graphene molecules are analyzed by the first
principle density functional theory to select suitable modification element.
Radical carbon modified C64H17 shows that the highest spin state is most
stable, which arises from two up-spin's tetrahedral molecular orbital
configuration at zigzag edge. In contrast, oxygen modified C59O5H17 show the
lowest spin state to be most stable due to four spins cancellation at oxygen
site. Boron modified C59B5H22 have no {\pi}-molecular orbit at boron site to
bring stable molecular spin state to be the lowest one. Whereas, C59N5H2 have
two {\pi}-electrons, where spins cancel each other to give the stable lowest
spin state. Silicon modified C59Si5H27 and Phosphorus modified C59P5H22 show
curved molecular geometry due to a large atom insertion at zigzag site, which
also bring complex spin distribution. Radical carbon and dihydrogenated carbon
modification are promising candidates for designing carbon-based magnetic
materials.
