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Energy differences between frozen core and all electrons correlated.
MP2, MP3, MP4, B2PLYP, CCSD, and CCSD(T)

For CH3CH2O (Ethoxy radical)

Energies in Hartree
Methods with standard basis sets
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Moller Plesset perturbation MP2=FULL -0.000957 -0.005006 -0.005006 -0.003592 -0.011815 -0.012699 -0.013119 -0.055548 -0.056274 -0.023168 -0.007299 -0.044459 -0.086390 -0.008395 -0.051633 -0.088124
MP3=FULL         -0.011550   -0.021609                  
Coupled Cluster CCSD(T)=FULL         -0.011579           -0.006809 -0.045605   -0.007892 -0.027533  
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ