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

For KH (Potassium hydride)

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) 6-311+G(3df,2p) TZVP
Moller Plesset perturbation MP2=FULL -0.013221 -0.000841 -0.002061 -0.000009 -0.000079 -0.000079 -0.000083 -0.106973 -0.107025 -0.000978 -0.129125 -0.031664
MP3=FULL         -0.000070   -0.000269       -0.124965 -0.034278
MP4=FULL   -0.000926     -0.000076       -0.104689   -0.125992  
B2PLYP=FULL -0.004346 -0.000289 -0.000722 -0.000003 -0.000024 -0.000024 -0.000025 -0.030325 -0.030340 -0.000292 -0.036748 -0.010009
Quadratic configuration interaction QCISD(T)=FULL         -0.000077           -0.125858  
QCISD(TQ)=FULL         -0.000076   -0.000080       -0.125686  
Coupled Cluster CCSD=FULL         -0.000073         -0.000941 -0.124767 -0.035177
CCSD(T)=FULL         -0.000076           -0.125845 -0.035661
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) TZVP