Calculating INTRAmolecular SAPT

Dear Developers,

I would like to calculate and understand intramolecular non-bonded interactions in transition states. The active complexes of interest are fully connected, thus normal SAPT would not be an option, but papters like J. Chem. Phys. 143, 051103 (2015) suggest me that there is some meaningful way for that as well.

Looking into the SI files of that paper I see that they are via plug-ins in Psi4. My question is if this feature is now incorporated into Psi4 somehow, and if I could obtain some minimal input to test it.

All input examples I found on F/I-SAPT: Functional Group and/or Intramolecular SAPT are actually featuring two molecules, while my case would be more like:

Also the video tutorial link

seems to be dead.

Many thanks in anticipation,


The example given in the manual is for a single molecule F/I-SAPT: Functional Group and/or Intramolecular SAPT

Dear hokru,

many thanks for your reply. Now what makes me a bit puzzled is that all the input examples are containing multiple molecules. Eg:
molecule mol {
0 1
O 0.39987 2.94222 -0.26535
H 0.05893 2.05436 -0.50962

0 1
O 0.48122 0.30277 -0.77763
H 0.26106 -0.50005 -1.28451

0 1
C 2.33048 -1.00269 0.03771


How do I proceed if my system is fully linked by covalent bonds (i.e. I only have one molecule), and how do I define my “functional groups” (i.e. the groups that are interacting with each other) then? In the paper I cite above, I do understand how it is done, but unfortunately that seems to be not implemented.



This is essentially the same input as for F-SAPT, except that the molecular system is now divided into three moieties – subsystems A and B whose intramolecular interaction we wish to compute, and a linking unit C.

So first the two functional groups, then the linking unit.