[Pw_forum] polarizability perpendicular to metal surface

[Garold Murdachaew]

Dear Pwscf forum members,

Can someone please tell me if it is possible to calculate the 
polarizability (tensor) per unit cell perpendicular to a metal surface 
(using finite field or other approach)?  Ideally, I would prefer to obtain 
the dynamic polarizability at imaginary frequencies to allow me to 
combine this with the corresponding property of an adsorbate in the 
Casimir-Polder formula for the C_6 dispersion coefficient.  Then, 
summing/integrating over the lateral unit cells of the surface I would 
be able to obtain the C_3 coefficient [as in, e.g., : I. Baraille, M. 
Rérat, and P.  Mora, "Ab initio calculations of the dispersion 
contribution to the physisorption potential: Application to the N_2-BN 
system", Phys. Rev. B 73, 075410 (2006)].

Thank you.
Garold Murdachaew
Postdoctoral Fellow - Condensed Matter Sector
SISSA-ISAS (International School for Advanced Studies)
email : murda at sissa.it
New Building, Room 208
Via Beirut 2-4, 34014 Trieste, Italy
tel   : +39 040 3787 477
fax   : +39 040 3787 528