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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 Be2 atoms 1 and 2

For Be2 (Beryllium 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 aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pCVDZ cc-pCVTZ
Moller Plesset perturbation MP2=FULL 0.0008 0.0013 0.0013 0.0013 -0.0738 0.0045 0.0046 -0.0849 0.0031 0.0134 0.0010 0.0042 0.0221 0.0200 0.0043 0.0171 0.0191 0.0052 0.0079
MP3=FULL         0.0719   -0.0743       0.0008 0.0041 0.0235            
MP4=FULL   0.0011     0.0043       0.0026     0.0040 0.0236   0.0042 0.0178      
B2PLYP=FULL 0.0004 -0.0076 -0.0076 -0.0015 0.0030 0.0030 0.0028 0.0032 0.0032 0.0120 0.0006 0.0036 0.0533   0.0039 0.0562      
Coupled Cluster CCSD=FULL         0.0042           0.0008 0.0039 0.0244 0.0209 0.0041 0.0184 0.0200    
CCSD(T)=FULL         0.0043           0.0007 0.0040 0.0249 0.0214 0.0042 0.0187 0.0204    
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-pCVDZ cc-pCVTZ

be2q1.gif