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

For BeH2+ (Beryllium dihydride 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) 6-311+G(3df,2p) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
Moller Plesset perturbation MP2=FULL -0.000404 -0.000734 -0.000734 -0.000797 -0.003389 -0.003550 -0.003619 -0.014657 -0.014804 -0.002628 -0.015685 -0.013126 -0.000873 -0.007740 -0.021447 -0.001479 -0.014239 -0.022211
MP3=FULL         -0.003593   -0.003836       -0.017239 -0.014639 -0.000889 -0.008194        
MP4=FULL   -0.000773     -0.003621       -0.016565   -0.017430   -0.000888 -0.008221   -0.001527 -0.015690  
B2PLYP=FULL -0.000128 -0.000230 -0.000230 -0.000248 -0.001041 -0.001083 -0.001105 -0.004293 -0.004335 -0.000803 -0.004607 -0.003848 -0.000271 -0.002271   -0.000454 -0.004110  
Quadratic configuration interaction QCISD(T)=FULL         -0.003613           -0.017413   -0.000881 -0.008093   -0.001509 -0.015507  
Coupled Cluster CCSD=FULL         -0.003569         -0.002633 -0.017294 -0.014778 -0.000860 -0.007995 -0.023537 -0.001479 -0.015389 -0.024356
CCSD(T)=FULL         -0.003613           -0.017414 -0.014836 -0.000880 -0.008096 -0.023710 -0.001509 -0.015512 -0.024532
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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ