Charge effect on TS (left, in black) and the DOS (right, in blue) of the AT nucleotide base pair. The (L-phosphate, R-phosphate) charges are (a) (0, 0), (b) (0, -1), (c) (-1, 0), (d) (0, -2), (e) (-2, 0), (f) (-1, -2), (g) (-2, -1) and (h) (-2, -2). The truth tables are summarized in Table 3.