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

For NCl+ (nitrogen monochloride cation)

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-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
Moller Plesset perturbation MP2=FULL -0.000182 -0.005851 -0.013557 -0.003604 -0.013473 -0.013473 -0.014313 -0.067540 -0.067540 -0.028916 -0.008258 -0.045713   -0.049231   -0.116769
MP3=FULL         -0.012379   -0.016268                  
Coupled Cluster CCSD(T)=FULL                         -0.090614   -0.091920  
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-pVTZ aug-cc-pVQZ cc-pV(T+d)Z