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

For CH(CN)3 (tricyanomethane)

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 cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ
Moller Plesset perturbation MP2=FULL -0.002233 -0.011764 -0.011764 -0.008796 -0.030579 -0.030757 -0.031845 -0.131082 -0.131246 -0.062586 -0.156145 -0.119316 -0.016110 -0.100931 -0.019258 -0.119556
MP3=FULL         -0.030025   -0.031309       -0.162101 -0.124383 -0.015071 -0.103850    
MP4=FULL   -0.011205                         -0.018118  
B2PLYP=FULL -0.000678 -0.003510 -0.003510 -0.002623 -0.009070 -0.009121 -0.009441 -0.037459 -0.037508 -0.018252 -0.044899 -0.034113 -0.004811 -0.029435 -0.005745 -0.034715
Quadratic configuration interaction QCISD(T)=FULL         -0.029925           -0.174367   -0.014908 -0.103916 -0.018012 -0.124045
Coupled Cluster CCSD=FULL         -0.029585         -0.063513 -0.161369 -0.124087 -0.014673 -0.102991 -0.017736  
CCSD(T)=FULL         -0.029947           -0.163049 -0.124919 -0.014918 -0.103941 -0.018021 -0.124075
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 cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ