Local σ-π mixing in C60 buckminsterfullerene

The local sigma-pi mixing phenomenon in C-60 buckminsterfullerene is quantified. To accomplish this, the localized orbitals spanning the space of fullerene's sigma and pi systems were orthogonalized and projected onto canonical molecular orbitals. The results show that there exist pi-type molecular orbitals which possess similar to 10% sigma character and vice versa. This strong mixing can be considered as a new evidence that contributes to the unconventional properties of fullerenes. The localized analysis detected bond bending for both sigma and pi bonds which were deviated from their framework for nearly 14 degrees. Also, several localized aspects of the pi system shows two types of pi bonds while the sigma bonds are fairly equivalent. (C) 2009 Elsevier B.V. All rights reserved.