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Comparison of levels of theory for C-I


Click on an entry for a histogram of the values.
The subscript refers to how many bonds of that type have been calculated.
average calculated bond lengths (Å)
Methods with predefined basis sets

average calculated bond lengths (Å)
Methods with standard basis sets
3-21G 3-21G* 6-31G* 6-311G* 6-311G** Def2TZVPP
hartree fock HF 2.1942
1
2.1785
1
  2.1546
2
  2.1301
2
density functional LSDA       2.1579
1
   
BLYP 2.2406
1
2.2198
1
  2.2135
2
   
B1B95   2.1677
1
  2.1522
2
   
B3LYP 2.2125
1
2.1935
1
  2.1804
2
  2.1692
2
B3PW91 2.1934
1
2.1759
1
  2.1643
2
   
mPW1PW91 2.1870
1
2.1700
1
  2.1576
2
   
M06-2X   2.1124
3
  2.1573
1
   
PBEPBE 2.2082
1
2.1887
1
  2.1834
2
  2.1714
2
PBE1PBE       2.1640
1
   
wB97X-D   2.1783
2
       
B97D3 2.2483
2
         
3-21G 3-21G* 6-31G* 6-311G* 6-311G** Def2TZVPP
Moller Plesset perturbation MP2 2.2038
1
2.1988
1
2.1756
2
2.1577
2
  2.1178
2
MP2=FULL 2.2027
1
2.1981
1
  2.1582
2
   
ROMP2       2.1642
1
   
Configuration interaction CID 2.2056
1
2.1951
1
  2.1481
2
   
CISD 2.2098
1
2.1969
1
  2.1494
2
   
3-21G 3-21G* 6-31G* 6-311G* 6-311G** Def2TZVPP
Quadratic configuration interaction QCISD 2.2185
1
2.2068
1
  2.1653
2
2.1573
1
 
QCISD(T) 2.2222
1
2.2127
1
  2.1683
1
   
Coupled Cluster CCD 2.2117
1
2.2035
1
  2.1610
2
   
CCSD(T) 2.2218
1
2.2124
1
  2.1678
1
2.1619
1
 
3-21G 3-21G* 6-31G* 6-311G* 6-311G** Def2TZVPP

average calculated bond lengths (Å)
Methods with effective core potentials (select basis sets)
daug-cc-pVDZ daug-cc-pVTZ daug-cc-pVQZ Sadlej_pVTZ CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF         2.1600
2
  2.1585
2
  2.1618
2
2.1679
2
density functional B1B95         2.1765
1
  2.1717
1
  2.1764
1
2.1832
1
B3LYP         2.1871
2
  2.1976
2
  2.1821
2
2.1918
2
Moller Plesset perturbation MP2         2.1802
2
  2.1780
2
  2.1818
2
2.1880
2
For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.