For two identical atoms, how to use an all electron basis set for one atom and a pseudopotential(ECP) for the other atom

[wangsy]

For example, in the calculation of an oxygen molecule, one O atom can be described using the def2-VTZP basis set, while the other O atom can be described using the Stuttgart RLC ECP basis set. How should the basis set section in the input file be written?

[jherbert]

This capability does not exist. It would essentially be the ‘BASIS = MIXED’ equivalent of ECP = …, but no such feature is implemented, as previously discussed here:

XANES of benzene using ECPs

Hi all, I want to calculate the XANES spectrum of benzene at the Carbon K-edge using the CVS-ADC(2)-x method. As the six Carbon atoms are equivalent I want to use effective core potentials for five of the carbon atoms and then calculate transitions starting from only one of the C(1s) orbitals but I don’t know how to properly set my input parameters. Do I set CC_REST_OCC to 1 as there is only 1 Carbon atom left? And how can I tell the program that I want ECPs for only 5 (and not all) Carbon atom…