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

For C6H6 (Hexa-1,5-diene-3-yne)

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) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ
Moller Plesset perturbation MP2=FULL -0.002611 -0.010030 -0.010030 -0.008116 -0.029088 -0.030235 -0.030842 -0.111560 -0.112461 -0.044997 -0.101980 -0.014924 -0.092638 -0.016765 -0.109611
MP3=FULL         -0.028945   -0.030592       -0.106910 -0.014114 -0.095749    
MP4=FULL   -0.009646     -0.029063       -0.117728     -0.014086 -0.096290 -0.015926  
B2PLYP=FULL -0.000792 -0.003014 -0.003014 -0.002432 -0.008677 -0.008969 -0.009147 -0.032013 -0.032261 -0.013227 -0.029259 -0.004477 -0.026994 -0.005026 -0.031810
Quadratic configuration interaction QCISD(T)=FULL         -0.028982             -0.014001 -0.096118 -0.015827  
Coupled Cluster CCSD=FULL         -0.028621         -0.044784 -0.106786 -0.013772 -0.095275 -0.015573  
CCSD(T)=FULL         -0.028994           -0.107525 0.022710 -0.096122 -0.015830  
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ