Example: QMMM with capping atoms

This is an example of QMMM using capping atoms. Capping atoms are added automatically when bonds are broken (between the QM and MM region). Because the amber forcefield is used the AtomicInfoForCappingAtom needs to be set, as the default type “H” is not an AMBER type.

Download QMMM_Butane.run

#! /bin/sh

"$AMSBIN/ams" <<eor

Task GeometryOptimization

GeometryOptimization
    Convergence Gradients=1E-4
End

System
    Atoms
        C  0.0000  0.0000  0.0000  region=QM  ForceField.Charge=0.0  ForceField.Type=CT
        H  1.0910  0.0000  0.0000  region=QM  ForceField.Charge=0.0  ForceField.Type=HC 
        H -0.3598  1.0300  0.0000  region=QM  ForceField.Charge=0.0  ForceField.Type=HC 
        C -0.5021 -0.7074 -1.2586  region=QM  ForceField.Charge=0.0  ForceField.Type=CT
        H -0.1397 -1.7383 -1.2662  region=QM  ForceField.Charge=0.0  ForceField.Type=HC 
        H -1.5949 -0.7053 -1.2662  region=QM  ForceField.Charge=0.0  ForceField.Type=HC 
        H -0.1307 -0.1841 -2.1433  region=QM  ForceField.Charge=0.0  ForceField.Type=HC 
        C -0.5195 -0.7318  1.2374  region=MM  ForceField.Charge=0.0  ForceField.Type=CT
        C -0.0376 -0.0530  2.5227  region=MM  ForceField.Charge=0.0  ForceField.Type=CT
        H  1.0524 -0.0554  2.5580  region=MM  ForceField.Charge=0.0  ForceField.Type=HC 
        H -0.3994  0.9752  2.5580  region=MM  ForceField.Charge=0.0  ForceField.Type=HC 
        H -0.4230 -0.5961  3.3860  region=MM  ForceField.Charge=0.0  ForceField.Type=HC 
        H -0.1631 -1.7630  1.2286  region=MM  ForceField.Charge=0.0  ForceField.Type=HC 
        H -1.6105 -0.7355  1.2286  region=MM  ForceField.Charge=0.0  ForceField.Type=HC 
    End
    BondOrders
        1 2  1.0
        1 3  1.0
        1 8  1.0
        1 4  1.0
        8 14 1.0
        8 13 1.0
        8 9  1.0
        4 5  1.0
        4 6  1.0
        4 7  1.0
        9 12 1.0
        9 11 1.0
        9 10 1.0
    End
End

Engine Hybrid
    QMMM
        QMRegion QM
        QMEngineID ADF
        MMEngineID ForceField
    End

    Capping
        AtomicInfoForCappingAtom ForceField.Type=HC ForceField.Charge=0.0
    End

    Engine ADF
      Basis
        Type DZP
      End
      Relativity
        Level None
      End
    EndEngine
    
    Engine ForceField
      Type Amber95
    EndEngine
EndEngine

eor