If you open a .cpk file in a plain‑text editor you’ll usually see something like:
– The Molecule Behind the File
| Resource | Link | |----------|------| | Avogadro – Free molecular editor | https://avogadro.cc/ | | Jmol – Interactive web viewer | https://jmol.sourceforge.net/ | | “Fragment‑Based Drug Discovery” – review (Nat. Rev. Drug Discov., 2020) | https://doi.org/10.1038/nrd.2020.123 | | Open‑source force fields for small molecules (OpenFF) | https://openforcefield.org/ | Dt30-g4.cpk
, it typically indicates a corrupted installation or an aggressive antivirus software quarantine. If you open a