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

Bond lengths, angles, or dihedrals given molecule at different levels of theory

The next several pages ask for
first - a molceule
second - a bond length, angle or dihedral, by choosing 2, 3 or 4 atoms in the molecule

Select species

Enter formula

The atom numbering does not line up between different methods for some species in the CCCBDB. This can lead to some erroneous geometry comparisons. We are working on correcting this.

Some experimental bond lengths are re values (bottom of well) and some are r0 (vibrational zero point level). The calculations yield re values. For diatomics the experimental values are mostly re. For polyatomics usually r0 is obtained from rotational spectra.

For polyatomics usually only a partial description of the geometry can be derived from the rotational constants, so assumptions are made in determining the geometry, such as all CH bonds in a methyl group have the same length.

Rules for chemical formula

Species in the CCCBDB