Quantum chemical calculation of molecular orbitals of A, B, and Zform of DNA: indications for conductivity

In this study we present DFT calculations of the molecular orbital of different forms of nucleic acids (A, B and Z) at the B3LYP/6-31 G* level we find that the level energies around the HOMO-LUMO gap in the double strand of A,B and Z are different. Regarding the hole (positive charge) and electron (excess electron) than transport in the DNA electrical conductivity, transfer of the holes involves propagation of electrons through DNA HOMOs but the later case involves excess electron propagation through unoccupied DNA orbital (LUMOs).