Ghost orbit

I he calculation of the energy of the individual species A is performed in the presence ol ghost orbitals of B that is, without the nuclei or electrons of B. A similar calculation is... 

There are variations of this method. For example may it be argued that the full set of ghost orbitals should not be used, since some of the functions in the complex are used for describing the electrons of the other component, and only the virtual orbitals are available for artificial stabilization. However, it appears that the method of full counterpoise corection (using all basis functions as ghost orbitals) gives the best results. Note that A cp is an approximate correction, it gives an estimate of the BSSE effect, but it does not provide either an upper or lower limit. 

E. Poliak The computation of Stine and Marcus for H3 was preliminary. I do not think that ghost orbits need be invoked but rather it is high time for a detailed and careful computation. 

A ghost orbital pt is imagined as being attached to each atom of the metal. This orbital represents that part of the wave function of the atom which is antisymmetric with respect to the plane of the ethylene molecule. It is supposed also that each atom contributes one electron. 

There have been many attempts to formulate a procedure to correct for BSSE and both a posteriori and a priori schemes are available [4]. The counterpoise approach (CP) [5], based on the use of "ghost orbitals , is the most common a posteriori procedure. Nevertheless, the addition of the partner s functions or ghost orbitals to counterbalance the BSSE does not provide a definite solution to the problem [6]. The introduction of the "secondary superposition error", upsetting the multipole moments and polarisabilities of the... 

Novel resonance effects occur in nonhydrogenic atoms in a strong magnetic field. As noted by Dando et al. (1995) these effects cannot be explained on the basis of hydrogenic periodic orbit theory. Their relation to ghost orbits is discussed by Hiipper et al. (1995). 

Figure 2.2 Approach of XH to ZH3, indicating effects of ghost functions. Molecular dipole moments are indicated by arrows. Any electron density which accumulates in the ghost orbitals is represented by the negative sign.

Alternate language that one may come across in the literature refers to the process of correcting AT to AE by including the ghost orbitals of each partner as the (Boys-Bernardi) counterpoise procedure.Using the basis set of the full complex at all stages (Eq. 4) is sometimes referred to as the dimer-centered basis set (DCBS) method, whereas discarding the basis functions of the partner for each subunit (Eq. 5) is termed the monomer-centered basis set (MCBS). 

N. S. Ostlund and D. L. Merrifield, Chem. Phys. Lett., 39, 612 (1976). Ghost Orbitals and the Basis Set Extension Effects. 

---