Dear QChem community,

I am having problems using the def2-TZVP basis set with iodine atom. Following the manual, beyond Rb atom the keyword “ECP def2-ecp” must be used (page 762 https://manual.q-chem.com/latest/qchem_manual.pdf): example 8.7 shows how to use it (8.12 Built-In ECPs‣ Chapter 8 Basis Sets and Effective Core Potentials ‣ Q-Chem 5.3 User’s Manual). However, when I use it in a simple HF calculation:

"

$molecule

0 1

H 0.0 0.0 0.0

I 0.0 0.0 1.5

$end

$rem

METHOD HF

BASIS DEF2-TZVP

ECP def2-ecp

$end

"

I obtain that the number of electrons is incorrect (it should be 27 alpha 27 beta electrons):

"

Molecular Point Group C*v NOp =***

Largest Abelian Subgroup C2v NOp = 1

Nuclear Repulsion Energy = 8.81962018 hartrees

There are 13 alpha and 13 beta electrons

Requested basis set is def2-TZVP

There are 20 shells and 56 basis functions

"

Do you know what is happening here? Thank you very much in advance for your help.