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NWChem FAQ

QM/MM


How do I run a QM/MM calculation?

You need to have an nwchem input file (example for K(H2O)6), and an associated pdb file (example for K(H2O)6). The PDB file must be complete, containing both the QM and MM atoms. The nwchem input file must contain a prepare section and fields relative to the QM region and the md inputs. A template follows (Note that the memory and eatoms value are only examples.) The example for K(H2O)6 contains comments with more information.

start SYSTEM

memory  heap 8 mb  stack 54 mb  global 54 mb

prepare
   system SYSTEM_CALC
   Define quantum atoms
   Add solvent
   update lists
end

basis
   basis set
end

scf
   SCF input
   print low
end

md
   system SYSTEM_CALC
   MD input
   memory 15000
end
qmmm
   eatoms -190.0
end
task qmmm scf ( energy | optimize | dynamics )
For detailes on the eatoms field, please have a look at the QM/MM section of the Users' Manual.


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Updated: February 22, 2005