The deviation in the N-and O-core ionization energy, obtained using the DMET-IP-CVS-EOM-CC at CC-PCVTZ basis set relative to the canonical method, is illustrated in Fig. and detailed in Table . Corresponding absolute values are summarized in Tables and. For N-core, the MUD and STDEV are 0.10 eV and 0.12 eV with a maximum error of 0.40 eV. Similar values of MUD and STDEV suggest a consistent and systematic shift.