Running NWChem

The command required to invoke NWChem is machine dependent, whereas most of the NWChem input is machine independent.

Sequential execution

To run NWChem sequentially on nearly all UNIX-based platforms simply use the command nwchem and provide the name of the input file as an argument. This does assume that either nwchem is in your path or you have set an alias of nwchem to point to the appropriate executable.

Output is to standard output, standard error and Fortran unit 6 (usually the same as standard output). Files are created by default in the current directory, though this may be overridden in the input.

Generally, one will run a job with the following command:

  nwchem input.nw >& input.out &

Parallel execution on UNIX-based parallel machines including workstation clusters using MPI

To run with MPI, parallel should not be used. The way we usually run nwchem under MPI are the following

• using mpirun:
  mpirun -np 8 $NWCHEM_TOP/bin/$NWCHEM_TARGET/nwchem input.nw

were $NWCHEM_TARGET values are described in the Compiling section.