ADF supports the QM/MM method to handle large systems or environment effects by treating only part of the atoms quantum-mechanically and the other ones by molecular mechanics. Use of this feature is invoked by the QM/MM keyword (block type). The functionality and all details of the keyword, involving quite a few options and aspects, are described in the separate QM/MM manual.
See also the pdb2adf utility, described in detail in the Utilities document, which transforms a PDB file into an ADF input file, for use with QM/MM.
