Subject: polarizability

From: Sompop Sanongraj <[email-masked]>
Date: Fri, 21 Jan 2000 16:54:07 -0500

Hi all
Can anyone point me out " what's the unit of polarizability that is
obtained from frequency calculation?"? I try to find from the manual but I
didn't see they have explained about the unit. It tell you about the
polarizability tensors. I don't know how to relate to the typical unit of
polarizability such as 10^-24 cm^3. 
Thanks
sompop 
Sompop Sanongraj
208 Church Street
Hancock MI 49930.

TEL: (906) 482 9377

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From: [email-masked]
Date: Sat, 22 Jan 2000 01:05:03 +0100

Hi Sompop,

In a classical picture, it can be shown that an atom has 

polarizability (alpha) ~ 4 (pi) (epsilon_o) (radius)^3

epsilon_o = 8.85419 x 10^-12   F m^-1 ( F = Farad)
               = 8.85419 x 10^-12   C^2 m^-2 N^-1

In MKS system, it gives unusual unit C^2 m N^-1 for polarizability. 
It is also expressed in volume polarizability: 

(alpha) / 4 (pi) (epsilon_o) 

which has units of m^3. In CGS units, where 4 (pi) (epsilon_o) = 1, 
the unit of polarizability is cm^3.

The polarizability increases with the number of electrons in the 
molecules, or with the volume of charge distribution.

For example the polarizability of CH_4 is 2.6 x 10^-24 cm^3
                                           of CCl_4 is 11.2 x 10^-24 cm^3

Jamal Uddin

On 21 Jan 00, at 16:54, Sompop Sanongraj wrote:

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