# Dipole Polarizabilities of Diatomic Molecules

1. Jun 6, 2015

### sams

Hello Everyone,

I have been recently calculating the static electric dipole polarizability αD of a polar diatomic molecule, but I was wondering how to calculate the components of the dipole polarizabilities αParallel and αPerpendicular of diatomic molecules? Any help is really appreciated.

Thank you very much for your time and consideration...

Regards,
Samir

2. Jun 7, 2015

### DrDu

So how did you calculate $\alpha_D$?

3. Jun 7, 2015

### sams

Using finite field theory by applying 0.005 a.u. external electric field strength. The molecule is taken along the z-axis and the calculated dipole polarizability is static. If we want to calculate the components we have to apply an external electric field along each of the three dimensional axis, and then? How can these components be calculated individually?

4. Jun 7, 2015

### DrDu

If the z-axis coincides with the bond axis, you calculated alpha_parallel. If you want the perpendicular part, you should chose the field perpendicular to the bond axis.

5. Jun 7, 2015

### sams

Exactly! But what is the procedure (calculation) to obtain these components???

6. Jun 7, 2015

### DrDu

Are you using some program?

7. Jun 7, 2015

### sams

Computational Chemistry package Molpro.

8. Jun 7, 2015

### DrDu

It's 15 years at least since I used molpro. Isn't there some option to specify the orientation of the electric field?

9. Jun 7, 2015

### sams

I think this is it: DIP,xfield,yfield,zfield;