National Institute of Standards and Technology

Computational Chemistry Comparison and Benchmark DataBase
Release 19	April 2018
NIST Standard Reference Database 101

I	Introduction
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III	Calculated data
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XIX	Index of properties
XX	H-bond dimers
XXI	Oddities

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III.G.7. (XIII.B.3.) (XIII.D.5.)

Compare vibrational frequencies for two calculations for N₂O⁺ (Nitrous oxide cation)

A = HF/6-31G*

B = MP2/6-31G*

scale factors=0.8985, 0.943

	symmetry			frequency (cm-1)					reduced mass (amu)					IR Intensity (km mol-1)
mode number	A	B		A	B	diff.	ratio		A	B	diff.	ratio		A	B	diff.	ratio
1	Σ	Σ		1923	3102	-1179.9	0.620		14.003	14.008	-0.005	1.000		1.06	56.88	-55.81	0.019
2	Σ	Σ		938	900	37.7	1.042		15.208	15.202	0.006	1.000		1.87	2.18	-0.31	0.858
3	Π	Π		457	606	-149.0	0.754		14.236	14.234	0.002	1.000		3.58	1.73	1.85	2.071
4	Π	Π		378	471	-92.6	0.803		14.236	14.234	0.002	1.000		4.53	2.21	2.32	2.049
scaled by				0.8985	0.943

See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.