CORINA

CORINA does not calculate "real" energies such as obtained from FF or QM calculations. Internally, CORINA uses symbolic energy values (that have been derived from FF calculations) only for ring systems.
For ring systems, a full conformational analysis is performed in order to identify a low-energy conformation.
Finally, the ring systems are relaxed in a so-called "pseudo" force field to optimize the ring skeletons, but without calculating "real" energies.

In general, CORINA does not have any limitations regarding the number of atoms or bonds of an input structure that should be converted into 3D. However, CORINA has been designed to process small to medium sized organic (typically "drug-like") molecules. The larger a molecules gets the more the intra-molecular interactions gain in importance influencing the secondary structure of a molecule. CORINA can model these interactions only to a limited extend and, therefore, is not able to correctly predict 3D structures of polymers and biopolymers such as proteins, enzymes or nucleic acids.

CORINA does not need the 2D information (or structure depict) of a molecule but the connection table (CT) information of a molecule. This information is provided in standard file formats for chemical information (such as MDL SDFile or SMILES). CORINA can also generate a 3D structure from an input SDFile if all (2D) coordinates are set to zero (SMILES also does not provide 2D information).
Since the first commercial version of CORINA, it is fully aware of stereochemistry.