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

For NH4+ (ammonium 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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
Moller Plesset perturbation MP2=FULL -0.000267 -0.001809 -0.001809 -0.001187 -0.003290 -0.003973 -0.004024 -0.018728 -0.019340 -0.009321 -0.017404 -0.002810 -0.016178 -0.030617 -0.003000 -0.017927 -0.031107 -0.016178
MP3=FULL         -0.003116   -0.003853       -0.017996 -0.002636 -0.016480          
MP4=FULL   -0.001707     -0.003117       -0.019905     -0.002616 -0.016573   -0.002803 -0.018451    
B2PLYP=FULL -0.000079 -0.000533 -0.000533 -0.000348 -0.000963 -0.001158 -0.001173 -0.005309 -0.005489 -0.002680 -0.004944 -0.000822 -0.004657   -0.000879 -0.005153    
Quadratic configuration interaction QCISD(T)=FULL         -0.003111             -0.002605 -0.016535   -0.002793 -0.018410    
QCISD(TQ)=FULL         -0.003112   -0.003834         -0.002604 -0.016534 -0.031820 -0.002791 -0.018409 -0.032339  
Coupled Cluster CCSD=FULL         -0.003080         -0.009436 -0.017959 -0.002576 -0.016404 -0.031567 -0.002762 -0.018269 -0.032078  
CCSD(T)=FULL         -0.003112           -0.018049 -0.002605 -0.016535 -0.031823 -0.002792 -0.018410 -0.032339  
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z