(A) η − θ from the complete-data set for nonhelical nucleotides with sugar conformation in North. Density contours of 
(X = 1, 2, or 4; dark red, violet, and dark blue, respectively) highlight regions of the plots with a significant population
of nucleotides. Cluster or HDRs previously identified by Pyle and coworkers are labeled in red, while new clusters found in
this work appear in dark green. Black dashed lines delimit the region occupied by canonical helical A-form. (B) Same as (A) for nucleotides in South configuration. (C) Representative structure for each new cluster found. (D) Example of the stacking analysis for cluster I North. ρ and z components of the R-vector (Bottaro et al. 2014) between the given nucleobase and its 5′ (green) and 3′ (pink) neighboring nucleobases are shown. The inner space between
ellipses and dotted lines shows the region in which stacking occurs. (E) Same as (D) for cluster I South. (F) Interaction energy between the given nucleobase and its 5′ (green) and 3′ (pink) neighboring for cluster I North. (G) Direct interaction energy between the 5′ and 3′ nucleobases (one to three interactions) for cluster I North. (H) Same as (F) for cluster I South. (I) Same as (G) for cluster I South.
