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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XXI	Oddities

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

Compare vibrational frequencies for two calculations for SSCl₂ (Thiothionyl chloride)

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'		563	730	-166.9	0.771		32.001	31.974	0.027	1.001		157.21	161.09	-3.88	0.976
2	A'	A'		425	338	86.5	1.256		33.175	32.807	0.368	1.011		154.18	122.27	31.90	1.261
3	A'	A'		262	229	32.6	1.142		33.164	33.254	-0.090	0.997		8.65	35.02	-26.37	0.247
4	A'	A'		195	150	45.1	1.301		34.224	34.523	-0.298	0.991		2.16	0.37	1.79	5.904
5	A"	A"		430	298	131.9	1.442		32.972	32.665	0.307	1.009		141.23	139.33	1.90	1.014
6	A"	A"		186	158	28.0	1.177		33.490	33.763	-0.273	0.992		1.28	21.77	-20.49	0.059
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.