Issue with the .fchk interface

Hello Developers,

I am new to Psi4, and have installed it through conda. Everything, that I’ve checked so far, seem to work fine. Except for the following input
#! CASSCF/6-31G** energy point

molecule {
H 1 1.00
H 1 1.00 2 103.1

set {
scf_type pk
basis 6-31G**
reference rhf
restricted_docc [1, 0, 0, 0]
active [3, 0, 1, 2]

casscf_energy = energy(‘casscf’)

energy, wfn = energy(‘scf’, return_wfn=True)
fchk_writer = psi4.FCHKWriter(wfn)

I was unable to generate the formatted checkpoint file. The following is the error message:

Traceback (most recent call last):
File “”, line 29, in
TypeError: ‘float’ object is not iterable

I’m not acquainted with Python either. I’m using the python from the conda install. Need your help.


This works fine for me. The error message that you are getting suggest that this line is only returning a float:

energy, wfn = energy('scf', return_wfn=True)

Older Psi’s did not have the return_wfn attribute and I’m guessing that either you need to update Psi4 by

conda update psi4

or that you have your PSIDATADIR set to an older version.

Thanks a lot. The update did the job for me.

Is it possible to write the state-averaged CASSCF orbitals and use them for future calculations, as is done in the case of SCF calculations (by file 180)?

Sorry, not at the moment. Im releasing a MCSCF update soon and I will add that to the list.

Hi Daniel,

Thanks. I look forward to the update.