From:	h8714031;at;hkuxa.hku.hk (Mok Kam Wah)
Date:	Thu, 21 Oct 93 15:17:45 WST
Subject:	Question on calculating vibrational frequency

Dear Netters,
     I am doing ab initio calculation on diatomics. I want to ask is it
justified to calculate vibrational frequency in the following way.

First to optimized to the equilibrium geometry.
Calculate the energy (say 0.01A) apart from the geometry.
Thus the potentail well mininium and a nearby point can then determine the
quadratic curve pass thru them.
Use 2 times the coeff of x**2 as the force constant and
     vibrational frequency = sqrt (force constant / isotopic mass)

Is the accuracy of this calculation similiar to the vibrational analysis
available in most Ab initio package?

K.W.Mok

--
K.W.Mok
E-Mail: h8714031' at \`hkuxa.hku.hk
Dept. of Chem., University of Hong Kong.


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