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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 Ca2 atoms 1 and 2

For Ca2 (Calcium diatomic)
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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ
Moller Plesset perturbation MP2=FULL 0.0400 0.0262 0.0769 0.0003 -0.4634 0.0027 0.0018 -0.4256 0.0103 0.0060 0.0759 0.2109 1.0085 0.2272
MP3=FULL         0.0025   0.0011       0.0424 0.1411 0.1788  
MP4=FULL   0.0177     0.0030       0.0193     0.1405 0.1899  
Coupled Cluster CCSD=FULL         0.0023           0.0804 0.2507 0.2024 0.1418
CCSD(T)=FULL         0.0018           0.0858 0.1510 0.1675 0.1287
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

ca2.gif