 


Example 3: P3+ / 6311G(2df) calculations of vertical
detachment energy (VEDE) of chloride ion
Input to G16 program:
#p ept(p3,ReadOrbitals) 6311G(2df)
Title: P3+ calculations for VEDEs of chloride ion.
1 1
Cl
4 4
This input is similar to the one of Example 1.
Calculations are carried out for chloride ion, which has 18 electrons in 9 molecular orbitals.
5 out of these 9 occupied orbitals will be frozen by default and the remaining occupied orbitals used for correlation
will be numbered from 1 through 4. The above input therefore requests (through the last line 4 4)
vertical electron detachment energy (VEDE) calculations from HOMO.
The resulting output gives this VEDE as:
Summary of results for alpha spinorbital 4 P3:
Koopmans theorem: 0.14401D+00 au 3.919 eV
Converged second order pole: 0.11439D+00 au 3.113 eV 0.911 (PS)
Converged 3rd order P3 pole: 0.12112D+00 au 3.296 eV 0.917 (PS)
Renormalized (P3+) P3 pole: 0.12027D+00 au 3.273 eV 0.916 (PS)
Similarly as in Example 1,
results are reported not only for P3+, but for Koopmans's theorem, D2 and P3, as well.
Pole strengths (PS) reported in the last column are equal to the norms of a Dyson orbitals corresponding to VEDEs
and are calculated from residues at VEDEs.
We reemphasize that:
PS values below 0.85 indicate that the diagonal selfenergy
approximations (i.e., D2, D3, OVGF, P3, P3+)
are unreliable!!!
Sign convention:
Numbers reported above are VEDEs
defined as the total energy of the Nelectron system minus the
total energy of the (N1)electron system. A negative value of VEDE
therefore means that the Nelectron system is bound. The above example
thus shows that the chloride ion is bound, i.e., it is energetically
more stable than the chlorine atom.
Note that instead of the 6311G(2df) basis, we could have used another
triplezeta quality basis containing polarization functions, e.g., the
correlationconsistent ccpVTZ basis.
 