Why is Iodine becoming Manganese when creating the .fchk file?

[chempanda]

Hello,

I’m pretty new to Psi4, and I am trying to generate a .fchk file for iodomethane with the following input.dat:

memory 1500 mb
set_num_threads (4)

molecule mol {

I -0.000001120230 -0.235257925013 0.000000000000
C 0.000007736812 1.921967634649 0.000000000000
H 0.516647802729 2.246305582223 -0.894827605797
H -1.033246667887 2.246327541223 0.000000000000
H 0.516647802729 2.246305582223 0.894827605797

}

set scf_type df
set basis def2-tzvpp
set reference uks

mol.update_geometry()
mol.symmetrize(1e-3)

e, wfn = energy(‘B3LYP’, return_wfn=True)
oeprop(wfn, “MULLIKEN_CHARGES”)
mol.print_out()
print_variables()
fchk(wfn, ‘basistest.fchk’)

When I run this file, the atomic numbers of basistest.fchk read:

Atomic numbers I N= 5
25 6 1 1 1

I believe the first number should be 53 if the atom is Iodine, but for some reason the atomic number is 25 which is manganese. From what I understand, the def2-tzvpp basis set should work with Iodine. I would greatly appreciate any advice on how to fix this problem.

[hokru]

Which psi4 version?
This is ECP related and should be fixed in the latest version.

[chempanda]

It is version 1.3.2. I’ll try updating to the latest version.

Thank you!