National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 22May 2022
NIST Standard Reference Database 101
IIExperimental data
IIICalculated data
IVData comparisons
VCost comparisons
VIInput and output files
VIITutorials and Units
VIIILinks to other sites
XOlder CCCBDB versions
XIII Vibrations
XIVReaction data
XVEntropy data
XVIBibliographic data
XVIIIon data
XVIIIBad calculations
XIXIndex of properties
XXH-bond dimers

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Converting between rotational constants and moments of inertia

Rotational constants are inversely related to moments of inertia:

B = h/(8 π2 c I)

Where B is the rotational constant (cm-1)
h is Plancks constant (gm cm2/sec)
c is the speed of light (cm/sec)
I is the moment of inertia (gm cm2)

Enter a rotational constant or a moment of inertia in the appropriate box below and press the adjacent calculate button. The related quantities will appear in the other boxes.

B cm-1
I gm cm2
I amu Å2