Specification of Ghost Atoms

To specify ghost atoms, use atom symbol G in zmat or geometry keywords:

  zmat = (
    he
    g 1 r
  )
  basis = "aug-cc-pVTZ"

Basis sets for ghost atoms must be defined explicitly using GHOST as the element name:

  basis:GHOST:"aug-cc-pVTZ": (
    ....
  )

This method leads to replication of existing basis set definitions. It is usually more convenient to specify ghost atoms as regular atoms with zero charge:

  zmat = (
    he
    he 1 r
  )
  charges = (2.0 0.0)
  basis = "aug-cc-pVTZ"

In this example, the second helium atom is a ``ghost'' atom which carries helium's aug-cc-pVTZ basis set.