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

For H2CN+ (hydrocyanonium 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-pVDZ aug-cc-pVTZ
Moller Plesset perturbation MP2=FULL -0.000622 -0.003331 -0.003331 -0.002396 -0.007813 -0.008096 -0.008424 -0.036750 -0.037042 -0.014597 -0.004519 -0.028268   -0.005158 -0.032929
MP3=FULL         -0.007559   -0.010353                
Coupled Cluster CCSD(T)=FULL         1.281308             -0.028832 -0.058712    
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