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Bond Length differences between FULL (all electrons correlated) and FROZEN core

Such as MP2=Frozen and MP2=Full
17 10 27 16 27

For CH+ atoms 1 and 2

For CH+ (Methylidyne cation)
Bond length differences (full - frozen) in Å. Mouse over a difference for the bond length with full correlation.
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) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVQZ
Moller Plesset perturbation MP2=FULL 0.0000 0.0000 0.0000 0.0000 0.0003 0.0010 0.0009 0.0002 0.0003 0.0019 0.0008 0.0081 0.0029 0.0009 0.0027
MP3=FULL         0.0003   0.0009                
Coupled Cluster CCSD(T)=FULL         0.0003               0.0033   0.0030
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVQZ

chq1.gif