Polarizability

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Hello Admins

I would like to know the procedure to compute the molecular polarizability "alpha" using the properties module of NWChem. My system has a total of 34 atoms (2 metals and ligands) and is a quadrivalent anion. The response keyword computes the electric polarizabilty and other parameters like tensors, etc. After reading through the properties section I learnt that the input should be like as below:

....
geometry
....
end
dft
....
end
properties
response 1 ... # order and frequency in hartree
velocity
end
task dft response

However I have not understood the frequency part. How should we select the value(s) to put in the input? should we do a frequency calculation before and find out the specific value? but even if so please explain in detail this concept.

Thanks and regards,
Mic

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The frequency for the response keyword is not related to the vibrational frequencies of your molecule but rather the frequency of the perturbing electric field. So if you want the static molecular polarizability, you would use a frequency of 0.0. If you are interested in the frequency dependent polarizability then you would use whichever frequency you are interested in. For example, if you are interested in a resonance Raman calculation, you would choose a frequency close to an electronic transition in your molecule.

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Thank you Sean for the response. I shall get back if I need to know anything else.

Thanks and Regards,

Mic

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Edited On 8:16:48 AM PST - Wed, Feb 10th 2016 by Hua


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