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

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
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
density functional LSDA 1.871 1.894 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    
SVWN   1.972     1.905 1.905 1.905 1.897 1.897 1.896     1.911 1.895   1.911 1.894       1.887    
BLYP 1.888 1.997 1.916 2.006 1.929 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 1.958 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   1.883 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 1.886 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       1.903 1.909 1.885   1.910 1.895       1.889    
Moller Plesset perturbation MP2 1.946 2.080 1.920 2.077 1.934 1.934 1.934 1.925 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 1.919 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    
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    
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

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 1.956 1.889 1.953 1.876 1.944 1.929
density functional B1B95 2.003 1.932        
B3LYP 2.007 1.933 2.005 1.925 1.997 1.974
Moller Plesset perturbation MP2 2.103 1.973 2.096 1.961 2.089 2.073
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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