Unbelievable induction energy in SAPT0

SAPT
1

Hello there, I am using this input file for SAPT0. I am getting quite positive induction energy for some systems under concern. But for related other systems, I am observing negative induction energy, which I believe is has to be.
I am attaching the input file, would you be kind enough to explain the highly positive induction term?

"
set basis aug-cc-pVTZ
molecule {
0 1
Cl 0.00000 0.78880 0.00000
Br 0.06952 -1.35210 0.00000

0 2
O -0.16772 3.73521 0.00000
H -1.09129 4.03237 0.00000
}

set {
reference uhf
freeze_core true
stability_analysis follow
soscf true
soscf_max_iter 30
soscf_print true
}

energy(‘sapt0’)
"

I am obtaining induction energy of 66.78964922 kcal/mol. Is there a problem with the code?

2

We are currently investigating if the stability following is faulty or not.
You can use it to check if the SCF is a minimum (stability_analysis check) but not to produce a minimum.
You might need to try different guesses to get sensible results.
see also https://github.com/psi4/psi4/issues/1747

1 Like
3

@hokru, I have seen in that github link that you are also facing this kind of problem.
Just for sake of asking, the system that you have chosen for calculation, which induction energy is much accurate?

4

The one with the huckel guess makes more sense and is likely correct. There the SCF also finds a stable minimum for each sub-calculations.

1 Like
5

I am using the similar inputs that you have used in the git-hub page. Some problems were solved, but for one system the problem persisted with guess huckel also.
I am uploading the input. It also has wavefunction unstability.

set basis aug-cc-pVTZ
molecule {
0 1
F -0.20621 -1.89055 0.00000
Cl 0.00000 -0.25407 0.00000

0 2
O 0.30354 2.32383 0.00000
H -0.57244 2.74358 0.00000
}

set {
reference uhf
guess huckel
freeze_core true
stability_analysis follow
soscf true
soscf_max_iter 30
soscf_print true
scf
maxiter 200
}

energy(‘sapt0’)