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

Compare vibrational frequencies for two calculations for CH₃ClH⁺ (methyl chloride, protonated)

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	A'	A'		3094	3116	-22.6	0.993		1.117	1.114	0.004	1.003		22.93	23.10	-0.17	0.993
2	A'	A'		2956	2983	-26.5	0.991		1.019	1.023	-0.004	0.996		0.75	2.11	-1.36	0.354
3	A'	A'		2751	2728	23.6	1.009		1.036	1.036	0.000	1.000		191.97	162.30	29.67	1.183
4	A'	A'		1414	1419	-4.7	0.997		1.061	1.052	0.009	1.009		16.74	20.95	-4.21	0.799
5	A'	A'		1352	1374	-22.6	0.984		1.101	1.110	-0.009	0.992		27.98	6.29	21.69	4.450
6	A'	A'		1085	1104	-19.7	0.982		1.171	1.200	-0.029	0.976		1.49	2.51	-1.02	0.593
7	A'	A'		733	761	-27.6	0.964		1.037	1.031	0.006	1.006		29.20	21.30	7.91	1.371
8	A'	A'		430	575	-145.1	0.748		8.437	8.060	0.376	1.047		131.08	59.61	71.47	2.199
9	A"	A"		3106	3130	-24.4	0.992		1.119	1.117	0.003	1.002		19.03	18.35	0.68	1.037
10	A"	A"		1415	1419	-4.1	0.997		1.063	1.055	0.008	1.008		18.13	22.42	-4.29	0.809
11	A"	A"		1006	1030	-23.5	0.977		1.124	1.147	-0.023	0.980		0.06	0.75	-0.69	0.084
12	A"	A"		181	214	-33.4	0.844		1.033	1.032	0.001	1.001		61.10	62.95	-1.85	0.971
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.