MacroModel Reference Manual - ISP

Chapter 4: Operation Codesarg6arg7arg8Coulombic electrostatic cutoffHydrogen bonding cutoffDefault: 4.0 Å. There is usually no reason to change this.Fmm cutoffAny fixed or frozen atoms are placed within this distance of a moving (SUBS) atomin a special class called Fmm. The Fmm atoms are treated in greater detail than theother fixed or frozen atoms in GB computations. All fixed and frozen atoms havetheir GB radii properly recomputed when the moving atoms move. When the polarizationfree-energy (Gpol) is computed, fixed-moving interactions are computedusing these updated GB radii. However, the GB contributions from pairs of fixed orfrozen atoms utilize the updated GB radii only when both fixed atoms are Fmm.Experiments performed so far have indicated that a reasonable value for CutFmm is8.0 Å, and this is the default.Regardless of the setting of arg8, the program does not allow the Fmm cutoff toexceed the larger of the van der Waals and the electrostatic cutoff.0 Default: 8.0 Å>0 Interpreted as cutoff in Å.