This system was immersed in a box of TIP3P water of dimension 15 × 15 × 15 nm 3 , and 18 sodium ions were added to neutralize the overall charge of the box. The AMBER99SB-ILDN force field was used for DNA and ions. A short MD simulation of 5 ns was performed in the NPT ensemble to optimize the density of the box. The velocity rescaling weak coupling scheme with a coupling constant of τ = 0.2 ps was used to maintain the reference temperature of 300 K. The pressure was maintained at 1 atm using the Berendsen barostat 51