NWChem/contrib/python/isodesmic.nw

start iso

mp2; freeze atomic; end

print none

python
  energies = {}

  c2h4 = '''
    geometry noprint
      symmetry d2h
      C 0 0     0.672
      H 0 0.935 1.238
    end
  '''

  ch4 = '''
    geometry noprint
      symmetry td 
      C 0     0     0
      H 0.634 0.634 0.634
    end
  '''

  h2 = '''
    geometry noprint
      H 0 0  0.378
      H 0 0 -0.378
    end
  '''
  
  def energy(basis, geometry):
    input_parse('''
      basis spherical noprint
        c library %s ; h library %s 
      end
    ''' % (basis, basis))
    input_parse(geometry)
    return task_energy('mp2')
 
  for basis in ('sto-3g', '6-31g', '6-31g*', 'cc-pvdz', 'cc-pvtz'):
     energies[basis] = 2*energy(basis, ch4) - \
                       2*energy(basis, h2)  - \
                         energy(basis, c2h4)
     if (ga_nodeid() == 0): print basis, ' %8.6f' % energies[basis]
end 


task python