Reading wavefunction to create fchk file

Hello, I’m trying to create fchk file from a saved wavefunction file, but it gives an error. I can access the energy or other properties such Mulliken charges from the wfn, but I couldn’t create the fchk file.

Input1(saving the wavefunction):

molecule {
H       -3.7108850795      0.2948899746     -0.7596908459                 
O       -3.3875552678      0.8040340127      0.0000000000                 
H       -2.4175552678      0.8040340127      0.0000000000                 
}

set basis sto-3g
energy, wfn = energy('scf',return_wfn=True)

wfn.to_file('h2o_wfn')

Input2(reading):

wfn = psi4.core.Wavefunction.from_file('h2o_wfn.npy')

fchk(wfn, "h2o.fchk")

Error:

KeyError: 'CURRENT ENERGY'

Thanks for the bug report. I’ve found the cause of the error and submitted a pull request to fix it, so this should be fixed for Psi4 1.6, which we are planning to release in May 2022.

If you need this fixed sooner, you’ll need to first wait for my fix to be accepted (which should be a day or two) and then either build Psi from source yourself or use our “between-version releases” called nightly.

Let me know which option you want to take, and I can give you further instructions.

1 Like

Thank you for quick response! I’ll wait the update. No need to rush.