[CP2K:4958] Berry phase dipole + smearing

[hut... at chem.uzh.ch]

Hi Matt

this is a highly nontrivial problem. If you want to get the 
basics, have a look at 
I Souza, T. Wilkens, RM Martin, PRB 62 1666 (2000)

Short version is:
- the Berry phase formula only applies to insulators, not metals
- for an insulator with variable occupation, you need a model
  for the all-electron wave function and then calculate 
  <Psi|exp(iGr)|Psi> where r=r1+r2+r3+... is. Maybe there is
  a way using ensemble density functional theory.

best regards

Juerg

--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie                  FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: cp... at googlegroups.com
From: Matt W 
Sent by: cp... at googlegroups.com
Date: 02/19/2014 12:53PM
Subject: [CP2K:4958] Berry phase dipole + smearing

Hi all,

I'm trying to do vibrational calculations using finite electronic temperature smearing for a periodic slab system.

At the moment Berry phase dipole moments aren't implemented, it seems, so no intensities. 

Could anyone give me some assistance to get them working (or point out that it is a fundamental problem). I'm thinking that it just needs rho%rho_ao(ispin)%matrix to be scaled by the occupation numbers appropriately in qs_moments, but maybe it is tougher?

Matt   
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