Thanks a lot for the questions. These structures are generated using the coordinate files (mmCIF format) downloaded from protein databases (like RCSB PDB) which is derived from X-ray diffraction and NMR studies. The backbone corresponds to coordinates of alpha-Carbon atoms for amino acids and Phosphorus atoms for RNA.
The secondary structure (helices and sheet) information are also present in these files which helps us make these structures. Since these structures are generated using mmCIF files, they look very similar to structures in RCSB PDB.
We did not perform additional statistical or thermodynamic calculations.
Hope this answers your question.