return to home page

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

Compare vibrational frequencies for two calculations for C4H4N2 (Pyrazine)

A = HF/6-31G*

B = MP2FC/6-31G*

  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   3056 3060 -4.0 0.999   1.101 1.101 -0.000 1.000   0.00 0.00 0.00  
2 Ag Ag   1625 1547 78.0 1.050   4.879 4.674 0.204 1.044   0.00 0.00 0.00  
3 Ag Ag   1222 1208 14.9 1.012   1.236 1.225 0.011 1.009   0.00 0.00 0.00  
4 Ag Ag   1016 982 34.4 1.035   5.396 5.870 -0.474 0.919   0.00 0.00 0.00  
5 Ag Ag   588 571 16.9 1.030   8.757 8.814 -0.057 0.994   0.00 0.00 0.00  
6 Au Au   1009 905 103.4 1.114   1.510 1.539 -0.028 0.982   0.00 0.00 0.00  
7 Au Au   383 324 59.1 1.183   2.419 2.349 0.069 1.030   0.00 0.00 0.00  
8 B1g B1g   941 890 50.3 1.057   1.259 1.259 0.000 1.000   0.00 0.00 0.00  
9 B1u B1u   3035 3042 -7.4 0.998   1.091 1.091 0.000 1.000   10.13 5.66 4.47 1.788
10 B1u B1u   1502 1444 58.2 1.040   2.086 1.862 0.224 1.120   1.28 3.99 -2.72 0.320
11 B1u B1u   1134 1109 24.8 1.022   1.858 2.163 -0.305 0.859   8.36 3.15 5.21 2.652
12 B1u B1u   1007 980 26.4 1.027   6.114 5.508 0.607 1.110   40.86 37.88 2.98 1.079
13 B2g B2g   988 894 93.5 1.104   1.358 1.187 0.170 1.144   0.00 0.00 0.00  
14 B2g B2g   752 704 48.3 1.069   3.753 6.184 -2.431 0.607   0.00 0.00 0.00  
15 B2u B2u   3050 3055 -5.1 0.998   1.096 1.096 0.000 1.000   72.35 48.81 23.54 1.482
16 B2u B2u   1413 1387 26.0 1.019   1.803 1.903 -0.100 0.948   45.74 33.87 11.87 1.351
17 B2u B2u   1081 1287 -206.0 0.840   2.183 7.727 -5.544 0.283   0.92 0.14 0.78 6.720
18 B2u B2u   1001 1049 -47.7 0.955   5.793 1.887 3.907 3.071   58.40 12.03 46.38 4.856
19 B3g B3g   3033 3041 -8.2 0.997   1.088 1.087 0.001 1.001   0.00 0.00 0.00  
20 B3g B3g   1589 1498 91.0 1.061   8.426 7.757 0.669 1.086   0.00 0.00 0.00  
21 B3g B3g   1345 1316 29.0 1.022   1.204 1.220 -0.015 0.987   0.00 0.00 0.00  
22 B3g B3g   700 677 22.8 1.034   6.931 6.931 -0.000 1.000   0.00 0.00 0.00  
23 B3u B3u   806 755 50.3 1.067   1.145 1.127 0.018 1.016   25.76 27.11 -1.36 0.950
24 B3u B3u   439 399 39.1 1.098   6.740 7.421 -0.681 0.908   28.82 24.34 4.48 1.184
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.