Table 1.

Properties of simulated systems

System number	System name	Dimensions of simulation box (Å)	Species present (concentration in M)	N/P ratio
I	PEI(20)	97 × 102 × 80	PEI with 20 repeating units, all protonated	1:1
			22 Na+ (0.05)
			20 Cl− (0.05)
II	PLL(20)	110 × 80 × 90	PLL with 20 lysine units, all protonated	1:1
			22 Na+ (0.05)
			20 Cl− (0.05)
III	50%-PEI(20)	95 × 100 × 80	PEI with 20 repeating units, 10 protonated	1:1
			27 Na+ (0.06)
			15 Cl− (0.04)
IV	50%-PEI(40)	107 × 117 × 70	PEI with 40 repeating units, 20 protonated	2:1
			22 Na+ (0.05)
			20 Cl− (0.05)
V	3-PEI(20)	107 × 100 × 110	Three PEI chains each with 20 repeating units with 10 protonated	3:1
			22 Na+ (0.03)
			30 Cl− (0.05)
VI	Na+	95 × 102 × 80	42 Na+ (0.09)	N/A
			20 Cl− (0.05)