MacroModel Program Capacity

MacroModel uses dynamic memory allocation. For most computations, the size of the system that can be studied is limited only by the resources of the computer on which the simulation is performed. Some compiled-in limits remain, and a few are described below:

  • MAXFV—The maximum number of atoms that can be used in certain second-derivative procedures. Opcodes that are affected by this limit are documented in the opcode descriptions. For this version of MacroModel MAXFV is 1100.

  • The maximum number of comparison atoms that can be specified is 20,000. In addition, the total number of fixed and frozen atoms cannot exceed 20,000. Structural restraints can be applied to sets of atoms, but the limit is 20,000 each of stretches, bends, and torsions.

The maximum number of structures that can be saved in a conformational search or multiple minimization is under user control. See: