We performed 100 ns-long molecular dynamics (MD) simulations of two 18-mers (GC-CGCGCGCGCGCGCGGC and GCGGGGGGGGGGGGGGGC, later named "GCGC" and "GGGG"), based on the systematic study conducted by the ABC consortium, 42 using the Amber force field for nucleic acids in its parmbsc0 version with χ OL3 modifications for RNA molecules, and SPC/E water molecules. Following the same strategy as in previous works by Auffinger and Westhof, we chose the 18-mers to contain only GC base pairs, so that the only chemical difference between the DNA and RNA systems is the sugar-ribose in RNA and deoxyribose in DNA. The preparation of the systems, simulation setup and structural analysis are detailed in Supporting Information.