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

Compare vibrational frequencies for two calculations for C6F6 (hexafluorobenzene)

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 A1g A1g   1507 1460 46.9 1.032   12.833 12.807 0.026 1.002   0.00 0.00 0.00  
2 A1g A1g   550 534 15.3 1.029   17.228 17.274 -0.047 0.997   0.00 0.00 0.00  
3 A2g A2g   769 731 38.6 1.053   12.663 12.657 0.006 1.000   0.00 0.00 0.00  
4 A2u A2u   219 201 18.6 1.093   13.996 13.996 0.000 1.000   12.17 6.09 6.08 1.999
5 B1u B1u   1336 1283 52.5 1.041   12.759 12.847 -0.088 0.993   0.00 0.00 0.00  
6 B1u B1u   575 564 11.0 1.020   17.364 17.204 0.161 1.009   0.00 0.00 0.00  
7 B2g B2g   606 195 410.7 3.102   12.086 18.576 -6.490 0.651   0.00 0.00 0.00  
8 B2g B2g   182 222i 403.9 -0.821   18.788 12.175 6.613 1.543   0.00 0.00 0.00  
9 B2u B2u   1084 1365 -281.5 0.794   12.004 12.001 0.003 1.000   0.00 0.00 0.00  
10 B2u B2u   264 249 14.5 1.058   18.989 18.997 -0.008 1.000   0.00 0.00 0.00  
11 E1g E1g   392 347 44.5 1.128   12.663 12.657 0.006 1.000   0.00 0.00 0.00  
12 E1g E1g   392 347 44.5 1.128   12.663 12.657 0.006 1.000   0.00 0.00 0.00  
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.