Influence of correlated electrons on the paramagnetism of DNA

Vadim Apalkov and Tapash Chakraborty

Phys. Rev. B 78, 104424 – Published 30 September 2008

Abstract

We address the fundamental role of electronic and vibrational interactions on the magnetization of the homogeneous and randomly sequenced DNA. We find several important magnetic properties of DNA: the intrastrand electron-electron interaction enhances magnetization, while the interstrand interaction suppresses it. Renormalization of the hopping integrals due to electron-vibration interactions results in a paramagnetic to diamagnetic transition as a function of temperature. The influence of interelectron interactions is therefore to transform the diamagnetic system into a paramagnetic one while the temperature can reverse that behavior. Being entirely intrinsic, these properties would not be influenced by the environment.

Received 27 May 2008

DOI:https://doi.org/10.1103/PhysRevB.78.104424

Authors & Affiliations

Vadim Apalkov¹ and Tapash Chakraborty^2,*

¹Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303, USA
²Department of Physics and Astronomy, University of Manitoba, Winnipeg, Canada, R3T 2N2

^*tapash@physics.umanitoba.ca

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Vol. 78, Iss. 10 — 1 September 2008

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Images

Figure 1
(a) Magnetic susceptibility of the poly(G)-poly(C) DNA molecule as a function of $α$ , which characterizes the suppression of the corresponding interaction potential, i.e., the interaction potential (2) is $α V_{x, x}$ . The potentials $V_{x, x}$ are shown next to the corresponding lines. The susceptibility of DNA without the electron-electron interaction is indicated along the left axis (as an arrow). (b) Same as in (a) but for the poly(A)-poly(T) DNA molecule.Reuse & Permissions
Figure 2
(a) Magnetic susceptibility of DNA versus the temperature shown for the double-stranded DNA model with electron-vibration interaction included. The electron system is noninteracting. The labels [GC] and [AT] correspond to the poly(G)-poly(C) and the poly(A)-poly(T) DNAs, respectively. The susceptibility of the poly(A)-poly(T) DNA is multiplied by 10. The inset shows schematically the hopping integrals as functions of the twist angle for the HOMO and LUMO strands of the poly(G)-poly(C) DNA. Here $θ_{0} = 36 °$ is the equilibrium twist angle. (b) Same as in figure (a) but with electron-electron interactions included.Reuse & Permissions
Figure 3
(a) The transition temperature versus the DNA composition. The labels (0) and (1) next to the lines correspond to noninteracting and interacting electron systems, respectively. (b) The paramagnetic and diamagnetic phases are shown in the $α − η$ plane (see text). The line AB marks the transition from A DNA to B DNA, which occurs at a fixed value of the DNA composition.Reuse & Permissions
Figure 4
(a) The transition temperature is shown as a function of DNA composition with modified hopping integrals for poly(A)-poly(T) DNA: $t_{H} = - 0.15 eV$ , $t_{L} = 0.08 eV$ , and $t_{LH} = 0.06 eV$ . The labels (0) and (1) next to the lines correspond to noninteracting and interacting electron systems, respectively. (b) Two different phases, paramagnetic and diamagnetic, are shown in the plane $U - η$ . Here $U$ characterizes the interaction strength, and $η$ determines DNA composition. The line AB illustrates the transition from A DNA to B DNA. The transition occurs at fixed value of DNA composition.Reuse & Permissions
Figure 5
(a) The susceptibility of generic DNA is shown as a function of DNA composition $η$ . The dashed lines illustrate the linear dependence described by Eq. (8). The labels (1) and (2) next to the lines correspond to partially random and random DNA sequences, respectively. The inset shows the effect of the random structure on the value of $η_{0}$ . (b) The susceptibility of generic DNA is shown as a function of DNA composition, $η$ , with modified hopping integrals for A-T base pairs: $t_{H} = - 0.15 eV$ , $t_{L} = 0.08 eV$ , and $t_{LH} = 0.06 eV$ . Labels (1) and (2) next to the curves correspond to partially random and random DNAs, respectively.Reuse & Permissions

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