return to home page

IV.D.1. (XII.C.1.)

Geometry Comparison

S2 (Sulfur diatomic)


distance is atom 1 (S) to atom 2 (S)

Experimental bond length is 1.889  Å

Display Options
Switch to bar chart display
Calculated bond length in Å
Methods with predefined basis sets
semi-empirical AM1 1.838
PM3 1.859
PM6 1.877
composite G2 1.878
G3 1.878
G3B3 1.929
G4 1.901
CBS-Q 1.878

Calculated bond length in Å
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 cc-pV(D+d)Z cc-pV(T+d)Z aug-cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ Sadlej_pVTZ
hartree fock HF 1.895 2.028 1.869 2.005 1.878 1.878 1.878 1.877 1.877 1.869 1.863 1.883 1.888 1.872 1.866 1.889 1.871 1.865 1.871 1.863 1.864 1.884 1.864 1.899
ROHF   2.021 1.867   1.876 1.876 1.876 1.875         1.886 1.869         1.871          
density functional LSDA 1.954 1.907 1.907 2.055 1.922 1.922 1.921 1.918 1.918 1.905     1.928 1.906   1.927 1.905   1.895          
SVWN   1.982     1.920   1.905                                  
BLYP 1.982 2.122 1.943 2.098 1.960 1.960 1.959 1.959 1.959 1.942     1.966 1.944   1.962     1.914          
B1B95 1.938 1.893 1.893 2.037 1.904 1.904 1.904 1.903 1.903 1.892     1.912 1.894 1.888 1.912 1.893 1.887 1.887 1.886 1.886 1.911 1.888  
B3LYP 1.956 2.086 1.915 2.064 1.929 1.929 1.929 1.928 1.928 1.914 1.903 1.911 1.936 1.916 1.909 1.935 1.914 1.908 1.900 1.903 1.902 1.931 1.905 1.942
B3LYPultrafine         1.930                       1.901              
B3PW91 1.948 2.073 1.904 2.050 1.916 1.916 1.916 1.915 1.915 1.903     1.924 1.904   1.921     1.893          
mPW1PW91 1.942 2.065 1.899 2.042 1.910 1.910 1.910 1.908 1.908 1.897     1.918 1.899   1.915     1.889          
M06-2X         1.895                                      
PBEPBE 1.968 2.101 1.925 2.076 1.939 1.939 1.939 1.938 1.938 1.923 1.911   1.945 1.925 1.919 1.944 1.924 1.918 1.904 1.911       1.922
PBEPBEultrafine         1.936                                      
PBE1PBE         1.909                                      
HSEh1PBE         1.908                                      
TPSSh         1.906   1.906             1.899                    
Moller Plesset perturbation MP2 1.994 2.213 1.923 2.168 1.939 1.939 1.939 1.937 1.937 1.926   1.918 1.954 1.927 1.899 1.959 1.926 1.899 1.902 1.900 1.900 1.932 1.901 1.957
MP2=FULL 1.994 2.215 1.922 2.169 1.937 1.937 1.937 1.937 1.937 1.919     1.953 1.923 1.896 1.958 1.919   1.900 1.895 1.892 1.931 1.897  
MP3         1.926   1.909                                  
MP3=FULL         1.908   1.907                                  
MP4   2.179     1.948     1.930 1.950         1.921         1.923          
B2PLYP         1.911                 1.904                    
Configuration interaction CID   2.118 1.898 2.088 1.910     1.907                                
CISD   2.124 1.900 2.093 1.913     1.910                                
Quadratic configuration interaction QCISD   2.163 1.916 2.124 1.930 1.930 1.930 1.929 1.929 1.916     1.945 1.916         1.898 1.895        
QCISD(T)         1.944     1.926         1.961 1.933   1.963 1.932              
Coupled Cluster CCD   2.150 1.911 2.114 1.925 1.925 1.925 1.923 1.923 1.912     1.939 1.911   1.941 1.910   1.896 1.891 1.891      
CCSD         1.929     1.913                                
CCSD(T)   2.128     1.943 1.925 1.925 1.925 1.925   1.904   1.960 1.932 1.917 1.963 1.931   1.919 1.906   1.935 1.906  
CCSD(T)=FULL         1.941               1.937 1.912 1.914 1.944 1.909   1.917 1.901 1.898 1.933 1.903  

Calculated bond length in Å
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 2.013 1.891 2.012 1.889 2.024 2.020
density functional B1B95 2.064 1.932        
B3LYP 2.080 1.944 2.078 1.943 2.096 2.084
Moller Plesset perturbation MP2 2.168 1.956 2.167 1.954 2.196 2.197
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
Please use the error report form to report problems.