CI calculation with orbitals from external source


is it possible to use detci as a CI solver for a reference wavefunction from a third software?
I was hoping for a way to directly load all the intergrals from an existing FCIDUMP file and pass them detci.

Alternatively loading the molecular orbital coefficients and basis set (from a molden file) could work, i.e. setting up a SCF wavefunction object, and then passing it as reference function to detci. But this seams more elaborate.

Hi chrst,

I am trying the same thing. Do you happen to have a solution already? Thanks.

What input do you have to work with?

I’m not aware of any way to read in integrals from an external source for use in Psi. Reading in orbitals gives you some options.

I am not sure what you mean by “input”. I guess you are referring to how FCIDUMP is generated. If so, my FCIDUMP is generated by CRYSCOR.

I was referring to FCIDUMP vs MOLDEN.

Psi4 doesn’t support this feature on its own. There’s a Psi4 plugin called Forte that gives you this feature. Example here.

It’s probably also worth mentioning there’s a Jupyter Notebook style tutorial on integrals in Forte here.