Transmission properties of molecular bridges between conducting leads, especially DNA,as DNA can be synthesized in any sequence, orientation and length, trapped between the nanoeletrodes has drawn many researchers interest to understand how far and how freely charges can move along the stacks of base pairs in DNA. Considering Donor-Bridge-acceptor system, conduction properties of DNA are described in terms of attenuation parameter β and current density J(x), the β value ranges from 0.1-1.4 Å-1 for DNA and lower values of which corresponds to weak distance dependence of charge transfer and higher to strong distance dependence. Studying HOMO-LUMO distribution and energy gap, 'Critical' Bridge length Nx is determined, less than this many no. of molecules, means N < Nx, promotes super exchange tunneling transition and If N > Nx transition is through hopping. The paper also discusses the simulation of DNA based electronic components e.g. diode and transistors.
The interest in molecular devices is growing and a number of organic molecules are being studied to achieve commercially viable technology in near future. DNA being the only molecule, which can be, synthesizes in any sequence, orientation and length is a potential candidate for fabrication of Nano devices. It is established fact that life processes are governed by communication through out the length of DNA by charge transfer. Thus, the study of charge transfer in DNA is of great importance in understanding and realisation of DNA based biomolecular electronics. We calculated the ionisation potential of all the four bases of DNA using Harteree Fock Equation with Moller Plesset second harmonic approximation. On the basis of ionisation potential charge transfer in DNA primers has been simulated with respect to sequence and length in light of design of diode, triode and transistors. This paper discusses the calculation of ionisation potentials of individual bases, charge transfer in terms of electron and hole migration. Besides design of electronic components, paper also discusses the application of these calculations in understanding DNA damage chemistry and their experimental validation.