National Institute of Standards and Technology

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

I	Introduction
II	Experimental data
III	Calculated data
IV	Data comparisons
V	Cost comparisons
VI	Input and output files
VII	Tutorials and Units
VIII	Links to other sites
IX	Feedback
X	Older CCCBDB versions
XII	Geometries
XIII	Vibrations
XIV	Reaction data
XV	Entropy data
XVI	Bibliographic data
XVII	Ion data
XVIII	Bad calculations
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 C₃ (carbon trimer)

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	Σg	Σg		1228	1147	80.8	1.070		12.000	12.000	0.000	1.000		0.00	0.00	0.00
2	Σu	Σu		2077	2054	23.7	1.012		12.000	12.000	0.000	1.000		1346.30	386.90	959.40	3.480
3	Πu	Πu		137	166	-28.3	0.829		12.000	12.000	0.000	1.000		2.13	20.17	-18.04	0.106
4	Πu	Πu		137	166	-28.3	0.829		12.000	12.000	0.000	1.000		2.13	20.17	-18.04	0.106
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.