Hi all,

I would like to evaluate a scalar function on a DFT grid and get a representation in the AO basis.

In the manual, I found psi4.core.NumIntHelper.potential_integral(), which seemed custom-made for this purpose. However, I don’t understand the expected data type:

List[psi4.core.Vector]

Indeed, I am not even 100% sure whether potential_integral() is what I want:

- Evaluate a function on the DFT grid.
- Pass the vector (array) with function values into the grid-integrate-function or grid object, and have Psi4 work out the AO representation.

An example would be very much appreciated.

### For the grid creation, I follow psi4numpy:

basis = psi4.core.BasisSet.build(mol, “ORBITAL”, psi4.core.get_global_option(“BASIS”))

sup = psi4.driver.dft.build_superfunctional(“PBE”, True)[0]

Vpot = psi4.core.VBase.build(basis, sup, “RV”)

Vpot.initialize()

xs, ys, zs, ws = Vpot.get_np_xyzw()

### Evaluate my potential or other scalar function on the grid.

Vgrid = Eval_potential(xs, ys, zs)

### Get a matrix object nAO-by-nAO

V_AO_rep = ?

Any suggestions?

All the best,

Thomas