National Institute of Standards and Technology

Computational Chemistry Comparison and Benchmark DataBase
Release 22	May 2022
NIST Standard Reference Database 101

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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 N₂O₄ (Dinitrogen tetroxide)

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	Ag	Ag		1450	1331	119.2	1.090		15.224	15.152	0.072	1.005		0.00	0.00	0.00
2	Ag	Ag		862	754	108.9	1.145		15.051	15.184	-0.132	0.991		0.00	0.00	0.00
3	Ag	Ag		414	237	177.0	1.746		15.545	15.481	0.064	1.004		0.00	0.00	0.00
4	Au	Au		59	99	-40.1	0.593		15.995	15.995	0.000	1.000		0.00	0.00	0.00
5	B1u	B1u		1386	1213	172.6	1.142		15.321	15.396	-0.075	0.995		435.51	386.13	49.38	1.128
6	B1u	B1u		794	689	105.2	1.153		15.162	15.089	0.073	1.005		223.10	219.82	3.28	1.015
7	B2g	B2g		807	597	209.9	1.352		14.266	14.291	-0.025	0.998		0.00	0.00	0.00
8	B2u	B2u		1831	1867	-35.3	0.981		14.616	14.619	-0.003	1.000		1197.44	209.78	987.66	5.708
9	B2u	B2u		334	181	152.6	1.842		15.922	15.919	0.003	1.000		0.10	0.20	-0.10	0.506
10	B3g	B3g		1807	1837	-30.2	0.984		14.506	14.594	-0.088	0.994		0.00	0.00	0.00
11	B3g	B3g		578	447	130.9	1.293		15.581	15.507	0.074	1.005		0.00	0.00	0.00
12	B3u	B3u		534	374	159.9	1.427		14.555	14.555	0.000	1.000		46.11	9.06	37.05	5.090
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.