Vibrations of Formaldehyde, CH2O, Vibration 1 (Home)

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Using PM6, the first vibrational mode of formaldehyde, a B2, occurs at 1100cm-1.  This corresponds to a vibrational period of 1/(1100x3x1010) seconds, or
 30.3x10-15 s, or 30.3 femtoseconds.  This is a very symmetric vibration in that the two halves of the potential curve have the same shape.

In this simulation, each frame represents 0.2 fs, and the display is 50 frames per second, so each second represents 10fs.  If, using a stopwatch,  you time all 10 complete vibrations, it'll come to about 30 seconds, therefore the simulation represents a total of 300fs.  From this it follows that each vibration takes about 30 fs, and has a frequency of 1/(3x1010x30x10-15) cm-1 or 1100 cm-1  in accordance with the results of the vibrational calculation.

Data set used by MOPAC:

  irc=1 drc cycles=846 t-priority=0.2
 Formaldehyde

  O         0.00000000 +0    0.0000000 +0    0.0000000 +0                     -0.4225
  C         1.21074828 +1    0.0000000 +0    0.0000000 +0    1    0    0       0.2366
  H         1.09713884 +1  122.0336155 +1    0.0000000 +0    2    1    0       0.0929
  H         1.09712655 +1  122.0249758 +1  180.0000000 +0    2    1    3       0.0929