  We model the electron clouds of nucleic acids in DNA as a chain of coupled
quantum harmonic oscillators with dipole-dipole interaction between nearest
neighbours resulting in a van der Waals type bonding. Crucial parameters in our
model are the distances between the acids and the coupling between them, which
we estimate from numerical simulations [1]. We show that for realistic
parameters nearest neighbour entanglement is present even at room temperature.
We quantify the amount of entanglement in terms of negativity and single base
von Neumann entropy. We find that the strength of the single base von Neumann
entropy depends on the neighbouring sites, thus questioning the notion of
treating single bases as logically independent units. We derive an analytical
expression for the binding energy of the coupled chain in terms of entanglement
and show the connection between entanglement and correlation energy, a quantity
commonly used in quantum chemistry.
