NWChem

class NWChem

This interface supports energy and gradient evaluations with the NWChem electronic structure package (version 7.0 or later)

An NWChem Theory object can be specified as follows:

my_frag = Fragment(...)

my_theory = NWChem(frag=my_frag,
                   method='hf',
                   basis='3-21g',
                   ...)

which would then be called as theory=my_theory in subsequent tasks (see Tasks).

General options

memory

(default: 400 MBytes) Maximum total memory (heap memory + stack memory + global memory) NWChem can request per process (MPI tasks): please note this does not take effect on directly linked NWChem but only standalone NWChem via a system call. Instead, use the command line argument to adjust the maximum memory that ChemShell-integrated global arrays (GA) can use for NWChem. For example, to request up to 1024 MB (default 1024, what is enough for most cases) global memory (2048 MB total memory):

chemsh --ga-memory 1024 input.py > output.log

mem_heap: (default: 100 MBytes) Maximum heap memory request per process: see memory

mem_stack: (default: 100 MBytes) Maximum stack memory request per process: see memory

mem_global: (default: 200 MBytes) Maximum global memory request per process: see memory

SCF options

tol_energy: (default: 1.E-6) SCF energy convergence threshold.

tol_density: (default: 1.E-5) SCF density convergence threshold.

tol_gradient: (default: 5.E-4) SCF gradient convergence threshold.