TS (left, in black) and DOS (right, in blue) of the RNA nucleotide base pairs. (a) AU, (b) GU and (c) RNA-CG. The spin state is the singlet state, and the (L-phosphate, R-phosphate) charges are (-1, -1). For GU base pairs, there is no \(TS(D_e)\) peak and no qubit states.