Table 1.

Structural parameters of natural DNA in B and A forms (43)

Structure type	a (Å)	H (Å)	g (Å−1)	G (Å−1)	N (G/g)	φ̃s (rad)	σ̄ (μC/cm2)
A	9	28.2	0.223	2.45	11	0.66π	22.1
B	9	33.8	0.186	1.86	10	0.40π	16.8

The radius a characterizes the location of centers of phosphate groups, and it is smaller than the van der Waals radius of DNA. σ̄ is calculated under the assumption that each phosphate has a unit elementary charge.