Subject: frequency errors

From: [email-masked] (Dave Young)
Date: Mon, 19 Dec 94 09:31:39 -0500

Hi,

	There was a question about why vibrational freqencies
are scaled by a factor of about 0.9 irregardless of method.

	The answer is that all of these frequencies are being
computed with a harmonic oscilator approximation.  For high frequency
modes, the difference between the harmonic oscilator prediction and
the exact or Morse potential like behavior is about 10% .
If you try to look at very low frequency modes, below a few
hundred wave numbers, you will see that the frequencies calculated
are off by a large amount.

				Dave Young
				[email-masked]
				youngdc@msucem

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	It can be easily shown that certain methods are not applicable
to solving the many particle Schrodinger equation.
	However, it has not been shown that it is impossible to find
an analytic solution.
	The only question remaining is "Who will have the honor?"
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