[molpro-user] Induced atomic dipole moments don't seem to be right (?)

Phillip Price pnprice at lbl.gov
Fri Mar 20 17:02:49 GMT 2009

Thanks to Kirk Peterson for helping me with an earlier question.

I'm a new Molpro user running 2006.1.

I need to calculate polarizability for some simple atoms and  
molecules.  I'm starting with atoms, to make sure I understand what  
I'm doing before moving on to more complicated systems.  Hydrogen  
works fine: apply a field of 0.001 a.u., use hf to predict the dipole  
moment, and divide by field to get the polarizability.  The result is  
correct to about 0.5% for hydrogen.

But I run into problems with helium: using HF-SCF or MRCI or RS3, I  
get about the right value for total energy, and the methods all pretty  
much agree on the polarizability...but it differs from the correct  
value (as quoted in CRC) by about a factor of 4.5.  (Specifically,  
using Molpro and a field of 0.001 a.u., the induced dipole moment is  
predicted to be 0.00079 Debye, which converts to a polarizability of  
0.0458 cubic angstroms.  CRC quotes a value of 0.205 cubic angstroms).

I am pretty low on the Molpro learning curve, so please accept my  
apologies if I am doing something silly.

Thanks for any help you can offer.

--Phil Price

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