Counterpoise Correct

Code author: Daniel G. A. Smith

_nbody_gufunc(func, method_string[, molecule, bsse_type, max_nbody, ptype, return_total_data])

Computes the nbody interaction energy, gradient, or Hessian depending on input. This is a generalized univeral function for computing interaction quantities.

Returns:

return type of func – The interaction data.

Returns:

(float, Wavefunction) – interaction data and wavefunction with energy/gradient/hessian set appropriately when return_wfn specified.

Parameters:

• func (function) –

  energy || etc.

  Python function that accepts method_string and a molecule. Returns a energy, gradient, or Hessian as requested.

• method_string (string) –

  'scf' || 'mp2' || 'ci5' || etc.

  First argument, lowercase and usually unlabeled. Indicates the computational method to be passed to func.

• molecule (molecule) –

  h2o || etc.

  The target molecule, if not the last molecule defined.

• return_wfn (boolean) –

  'on' || 'off'

  Indicate to additionally return the Wavefunction calculation result as the second element of a tuple.

• bsse_type (string or list) –

  'cp' || ['nocp', 'vmfc'] || None || etc.

  Type of BSSE correction to compute: CP, NoCP, or VMFC. The first in this list is returned by this function. By default, this function is not called.

• max_nbody (int) –

  3 || etc.

  Maximum n-body to compute, cannot exceed the number of fragments in the moleucle.

• ptype (string) –

  'energy' || 'gradient' || 'hessian'

  Type of the procedure passed in.

• return_total_data (boolean) –

  'on' || 'off'

  If True returns the total data (energy/gradient/etc) of the system, otherwise returns interaction data.

The nbody function computes counterpoise-corrected (CP), non-CP (noCP), and Valiron-Mayer Function Couterpoise (VMFC) interaction energies for complexes composed of arbitrary numbers of monomers.

Examples :

# Counterpoise corrected CCSD(T) energy for the Helium dimer
molecule mol {
  He
  --
  He 1 3
}

energy('CCSD(T)', bsse_type='cp')

# noCP, VMFC, and CP energy for a helium cluster, limited at 3 bodies
molecule mol {
  He 0 0 0
  --
  He 0 0 4
  --
  He 0 4 0
  --
  He 4 0 0
}

# Returns the nocp energy as its first in the list
energy('CCSD(T)', bsse_type=['nocp', 'cp', 'vmfc'], max_nbody=3)