# [CP2K-user] How to calculate the dipole moment and polarizability for a OH bond?

jia huangji... at gmail.com
Tue Apr 9 04:36:52 UTC 2019

Dear CP2K users,

I am trying to calculate the dipole moment and polarizability for *each OH
bond* in a bulk water system (32 water in a cubic box with PBC).  The input
file (H2O32_md.inp; pos.inc) for DFT MD simulation is attached here.

Here is my method to calculate the dipole moment for each OH bond.
I can use the Wannier centers to calculate the dipole moment for each water
molecule (using $\mu = \sum_i Z_i R_i -2 r^w_n$), and therefore the dipole
moment of each OH bond in each water molecule.  This method works, but it
is not very direct from CP2K code.

But for the polarizibility, even though I can obtain the
polarizaibility (see PS) of the whole system,  I still do not know the
method to extract the polarizability for neither each water molecule or OH
bonds in them.

My question is: With *CP2K*, is it possbile to directly calculate *the
dipole moment vector and polarizibility tensor* for *a OH bond* in a water
molecule for the bulk water system?

With best regards,
jia

PS: the first 3 lines of the result for the polarizibility for the whole
system:

jia at xil /home/jia/H2O32_md [16]\$ head H2O32_md-1.polar
#   Step   Time [fs]           xx [a.u.]           xy [a.u.]           xz
[a.u.]           yx [a.u.]           yy [a.u.]           yz [a.u.]
zx [a.u.]           zy [a.u.]           zz [a.u.]
0       0.000        268.31915474          1.84753325
-7.77104321          1.80422537        273.71170715          2.58088055
-7.78446655          2.56412737        271.68321643
1       0.500        268.28862178          1.67253194
-7.78792499          1.63612816        274.88797255          3.09590223
-7.80366438          3.08627690        273.27103200
2       1.000        269.95417495          1.47505442
-7.87087433          1.44141475        277.68566066          3.65694561
-7.89349554          3.63530079        276.41211218

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