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Geometry Comparison

P2 (Phosphorus diatomic)


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

Experimental bond length is 1.893  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical AM1 1.694
PM3 1.715
PM6 1.820
composite G2 1.859
G3 1.859
G3B3 1.904
G4 1.885
CBS-Q 1.859

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 daug-cc-pVTZ
hartree fock HF 1.808 1.929 1.853 1.938 1.859 1.859 1.859 1.854 1.855 1.855 1.850 1.862 1.867 1.857 1.853 1.870 1.857 1.853 1.857 1.851 1.852 1.865 1.852 1.858
density functional LSDA 1.871 1.972 1.894 1.981 1.905 1.905 1.905 1.897 1.897 1.896   1.904 1.911 1.895   1.911 1.894   1.898 1.888 1.887      
BLYP 1.888 1.997 1.916 2.006 1.906 1.929 1.929 1.922 1.923 1.919   1.927 1.932 1.918   1.934     1.920 1.911 1.911      
B1B95 1.855   1.883 1.966 1.889 1.891 1.891 1.886 1.886 1.885   1.889 1.898 1.883   1.896 1.882   1.884 1.877 1.876      
B3LYP 1.865 1.972 1.893 1.982 1.904 1.904 1.904 1.898 1.898 1.895 1.888 1.904 1.909 1.895 1.890 1.910 1.895 1.890 1.897 1.889 1.888      
B3LYPultrafine         1.904             1.904 1.909 1.895   1.910 1.885       1.888      
B3PW91 1.861 1.968 1.890 1.974 1.898 1.898 1.898 1.891 1.891 1.890   1.898 1.904 1.891   1.905     1.892 1.884 1.884      
mPW1PW91 1.856 1.963 1.885 1.969 1.893 1.893 1.893 1.886 1.886 1.886   1.893 1.899 1.886   1.901 1.886   1.888 1.880 1.880      
M06-2X 1.841 1.946 1.874 1.957 1.883 1.883 1.883 1.877 1.877 1.877 1.872 1.883 1.889 1.878   1.891 1.877   1.879 1.872 1.872      
PBEPBE 1.880 1.989 1.910 1.996 1.920 1.920 1.920 1.913 1.913 1.911 1.904 1.919 1.925 1.911   1.926 1.911   1.913 1.904 1.904      
PBEPBEultrafine         1.920             1.919 1.925 1.911   1.925 1.911       1.904      
PBE1PBE 1.855   1.886 1.970 1.894 1.894 1.893 1.887 1.887 1.887   1.894 1.900 1.887   1.901 1.887       1.881      
HSEh1PBE 1.856 1.965 1.887 1.972 1.895 1.895 1.895 1.889 1.889 1.888   1.895 1.901 1.888   1.903 1.888   1.889 1.882 1.882      
TPSSh   1.975 1.895 1.979 1.890 1.902 1.890 1.896   1.885   1.903 1.909 1.885   1.910 1.895       1.889      
wB97X-D     1.871   1.877   1.877   1.872     1.877 1.877 1.872     1.872              
B97D3   1.940     1.898   1.898   1.894   1.887 1.915   1.892     1.906             1.906
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 daug-cc-pVTZ
Moller Plesset perturbation MP2 1.946 2.080 1.920 2.077 1.907 1.934 1.934 1.901 1.926 1.928   1.937 1.948 1.926 1.917 1.952 1.927 1.917 1.934 1.919 1.920 1.945 1.919  
MP2=FULL 1.945 2.081 1.918 2.077 1.932 1.932 1.932 1.925 1.925 1.919   1.938 1.947 1.922 1.914 1.950 1.914 1.913 1.931 1.912 1.910 1.944 1.914  
MP3         1.897   1.889         1.902 1.913 1.894         1.902 1.889 1.890      
MP3=FULL         1.887   1.887         1.903 1.912 1.891             1.882      
MP4   2.052     1.932     1.925 1.925     1.939 1.949 1.929   1.953 1.929   1.935 1.922 1.923      
MP4=FULL   2.054     1.930       1.926       1.947 1.925   1.951 1.922       1.914      
B2PLYP 1.889 2.009 1.905 2.016 1.917 1.917 1.917 1.910 1.910 1.909   1.918 1.925 1.893   1.927 1.909   1.912 1.902 1.902      
B2PLYP=FULL 1.889 2.010 1.904 2.016 1.917 1.917 1.916 1.910 1.910 1.906   1.918 1.924 1.908   1.926 1.907       1.899      
B2PLYP=FULLultrafine         1.917               1.924 1.908     1.907              
Configuration interaction CID   1.982 1.880 1.990 1.891     1.882                         1.877      
CISD   1.985 1.883 1.993 1.893     1.885                         1.879      
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 daug-cc-pVTZ
Quadratic configuration interaction QCISD   2.012 1.899 2.019 1.911 1.911 1.911 1.902 1.902 1.904   1.914 1.924 1.902   1.927 1.902   1.911 1.896 1.896      
QCISD(T)         1.922     1.914       1.928 1.939 1.917   1.942 1.917   1.926 1.911 1.911      
Coupled Cluster CCD   2.006 1.894 2.013 1.905 1.905 1.904 1.896 1.896 1.898   1.908 1.918 1.896   1.921 1.896   1.906 1.890 1.890      
CCSD         1.909     1.900       1.912 1.922 1.900 1.889 1.925 1.900 1.889 1.909 1.894 1.894      
CCSD=FULL         1.907             1.912 1.920 1.896 1.887 1.923 1.893 1.886     1.885      
CCSD(T)   2.021     1.921 1.921 1.921 1.913 1.913   1.907 1.926 1.937 1.916 1.905 1.941 1.916 1.905 1.925 1.910 1.910 1.935 1.910  
CCSD(T)=FULL         1.919             1.927 1.935 1.912 1.902 1.939 1.909 1.902 1.923 1.906 1.901 1.933 1.905  
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 daug-cc-pVTZ

Calculated bond length in Å
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD cc-pVTZ-PP aug-cc-pVTZ-PP Def2TZVPP
hartree fock HF 1.956 1.889 1.953 1.876 1.944 1.929     1.853
density functional B1B95 2.003 1.932              
B3LYP 2.007 1.933 2.005 1.925 1.997 1.974     1.881
PBEPBE                 1.891
Moller Plesset perturbation MP2 2.103 1.973 2.096 1.961 2.089 2.073     1.897
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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