Contents lists available at ScienceDirect Current Applied Physics journal homepage: www.elsevier.com/locate/cap Contemplating charge transport by modeling of DNA nucleobases based nano structures Rajan Vohra * , Ravinder Singh Sawhney, Kunwar Partap Singh Department of Electronics Technology, Guru Nanak Dev University, Amritsar, India ARTICLE INFO Keywords: Adenine DNA Extended Huckel theory Thymine Transmission spectra ABSTRACT Electrical charge transport through two basic strands Thymine and Adenine of DNA has been analyzed using jellium model approach. The FFT-2D computations have been performed for semi empirical Extended Huckel Theory using Atomistix Tool kit to contemplate the charge transport metrics like current and conductance. We have scrutinized the behavior of the devices in the range of -2 V–2 V for a step size of 0.2 V. A prominent observation is the drop in HLGs of Adenine and Thymine, when working as device as compared to their intrinsic values and this is comparative more visible in case of Adenine. The current in the thymine based device exhibit linear increase with voltage in spite of having low conductance. Further the broader transmission peaks re- present the strong coupling of electrodes to the scattering molecule (Thymine). The NDR effect of Adenine based device for higher bias can be utilized in various future electronics applications. 1. Introduction “There is plenty of room at the bottom” [1] by Nobel Prize winner Richard P. Feynman led to the field of nanotechnology and many re- searchers started to have a sudden keen interest in this field. So over the years the study for the use of single molecules and their performance in the field of electronics has really gathered pace. There have been many single molecules which have shown promising features but there is further a need for a molecular wire to further miniaturize the circuit. So the idea of using the DNA came into being. German biochemist Fre- derich Miescher was the first to notice a DNA in 1869 but its value was not perceived for many years. Watson, Crick and Wilkins [2] were conferred with the Nobel Prize in Medicine in 1962 for their findings related to the arrangement of nucleic acids and its importance in ex- change of info. DNA over the years has been researched for con- ductance and it has shown good conductivities and also it has the added benefit of self-assembling and organizing feature and it is an organic molecule which has been perfected over the period of many years by the nature by being tested in harsh conditions. Further in the DNA there are four bases A, T, C and G. There has been extensive research into the charge transport mechanism in the DNA and various theories proving the charge transport have been found to exist. We have also seen that conductance in DNA varies with the change in length [3–5], sequencing [6], nucleotide content [7], mechanical stretching [8], electrode ma- terial [9], Miller Indices orientation [10] and also the effect of AC electrical characterization on DNA. So we can say that the CT me- chanism in DNA is dependent on the four main constituents i.e. the four bases of DNA and encourage us to work on individual base of DNA. In the same pace for this paper we modeled and simulate the two bases of AT base pair of DNA using the SE-EHT along with FFT-2D computation within the variegated bias range of -2 V–2 V with step size of 0.2 V such that region of energy hold by these potentials comprises the bias window. Till now there has been a large number of researches on the charge transport mechanism in a DNA and the charge transport falls under three terms [11], Electron tunneling from donor to acceptor, Charge hopping between different base orbitals and amalgamation of the two. In the first category the charge transport it is assumed that the DNA behaves as a 1-D aromatic crystal with π electron conductivity [12,13]. This suggests that charge transfer takes place along the 1-D passage made by overlap between π orbitals in adjoining base pairs. The elec- trons do not interchange any energy with the molecules and are therefore never localized [12]. In the second category the charge transport includes the transport of charges through the base pairs. It takes place in multi steps over a large distance and electrons do inter- change energy with the molecules [14–16]. The transport shows weak reliance on the distance between the Donor and Acceptor sites. It has been found from equation (1) that rate of charge transport shows an experimental vulnerability on distance β , between the donor and ac- ceptor sites [17]. https://doi.org/10.1016/j.cap.2020.02.016 Received 14 October 2019; Received in revised form 14 February 2020; Accepted 24 February 2020 * Corresponding author. E-mail addresses: rajanvohraece.rsh@gndu.ac.in (R. Vohra), sawhney_gndu@hotmail.com (R.S. Sawhney), kunwarpartap.singh@gmail.com (K.P. Singh). Current Applied Physics 20 (2020) 653–659 Available online 28 February 2020 1567-1739/ © 2020 Korean Physical Society. Published by Elsevier B.V. All rights reserved. T