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Compare vibrational frequencies for two calculations for C6H4Cl2 (1,4-dichlorobenzene)


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)   Raman Activity (Å4/u)
mode number A B   A B diff. ratio   A B diff. ratio   A B diff. ratio   A B diff. ratio
1 Ag Ag   3066 3074 -8.1 0.997   1.097 1.097 -0.000 1.000   0.00 0.00 0.00            
2 Ag Ag   1608 1562 46.4 1.030   5.432 6.073 -0.641 0.894   0.00 0.00 0.00            
3 Ag Ag   1169 1158 10.3 1.009   1.151 1.131 0.020 1.018   0.00 0.00 0.00            
4 Ag Ag   1078 1077 1.6 1.001   8.150 7.997 0.153 1.019   0.00 0.00 0.00            
5 Ag Ag   734 728 5.4 1.007   7.211 7.162 0.049 1.007   0.00 0.00 0.00            
6 Ag Ag   319 316 2.9 1.009   26.906 26.214 0.691 1.026   0.00 0.00 0.00            
7 Au Au   988 832 155.7 1.187   1.352 1.267 0.085 1.067   0.00 0.00 0.00            
8 Au Au   413 381 31.6 1.083   2.978 3.493 -0.516 0.852   0.00 0.00 0.00            
9 B1g B1g   843 761 81.6 1.107   1.246 1.246 -0.000 1.000   0.00 0.00 0.00            
10 B1u B1u   3051 3061 -9.8 0.997   1.091 1.090 0.001 1.001   2.65 0.71 1.94 3.736          
11 B1u B1u   1490 1448 41.8 1.029   2.173 2.249 -0.076 0.966   114.69 102.66 12.02 1.117          
12 B1u B1u   1088 1078 10.1 1.009   2.124 2.024 0.101 1.050   117.28 87.80 29.47 1.336          
13 B1u B1u   997 973 23.7 1.024   4.398 4.629 -0.231 0.950   55.97 55.56 0.41 1.007          
14 B1u B1u   530 534 -4.5 0.992   9.471 9.228 0.242 1.026   35.39 24.24 11.16 1.460          
15 B2g B2g   974 813 160.7 1.198   1.356 1.076 0.280 1.260   0.00 0.00 0.00            
16 B2g B2g   696 444 252.5 1.569   3.714 12.007 -8.294 0.309   0.00 0.00 0.00            
17 B2g B2g   295 277 17.8 1.064   7.167 7.482 -0.315 0.958   0.00 0.00 0.00            
18 B2u B2u   3065 3073 -8.3 0.997   1.097 1.097 0.000 1.000   5.48 0.85 4.64 6.463          
19 B2u B2u   1393 1393 -0.3 1.000   2.587 5.336 -2.749 0.485   9.78 2.23 7.56 4.390          
20 B2u B2u   1132 1343 -210.6 0.843   2.909 3.955 -1.047 0.735   2.80 4.39 -1.59 0.637          
21 B2u B2u   1068 1084 -16.3 0.985   2.181 1.336 0.845 1.632   0.26 4.72 -4.45 0.056          
22 B2u B2u   214 212 2.3 1.011   12.484 12.467 0.017 1.001   1.44 1.01 0.43 1.422          
23 B3g B3g   3052 3062 -10.2 0.997   1.091 1.090 0.001 1.001   0.00 0.00 0.00            
24 B3g B3g   1590 1551 39.5 1.025   6.829 7.599 -0.770 0.899   0.00 0.00 0.00            
25 B3g B3g   1296 1257 39.0 1.031   1.266 1.243 0.023 1.019   0.00 0.00 0.00            
26 B3g B3g   621 604 16.7 1.028   7.147 7.166 -0.019 0.997   0.00 0.00 0.00            
27 B3g B3g   347 340 7.2 1.021   4.881 4.905 -0.024 0.995   0.00 0.00 0.00            
28 B3u B3u   844 737 107.0 1.145   1.465 1.339 0.126 1.094   62.62 65.81 -3.20 0.951          
29 B3u B3u   495 444 51.4 1.116   2.934 3.623 -0.689 0.810   18.11 11.43 6.68 1.584          
30 B3u B3u   102 96 6.0 1.063   12.239 12.131 0.108 1.009   0.91 0.59 0.32 1.546          
scaled by     0.8985 0.943
19 08 20 15 07

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.