[Pw_forum] electrical polarization calculations for non-collinear magnetism

[Paolo Giannozzi]

On Mar 28, 2009, at 6:25 , Xun-Wang Yan wrote:

>  nspin=1 and nspin=2 cases is supported,   there is not   
> noncolin=.true.  case.
> how to modify the bp_c_phase.f90 to include the noncolin=.true.  
> case for electric
> polarization calculation?

I know nothing about polarization and noncolinear calculations, but  
basically
what you need in a polarization calculation is a sequence of scalar  
products
between electronic states at different k-points. In the case of  
noncolinear
calculations, electronic states are spinors and are expanded into plane
waves with both spin-up and spin-down components. Coefficients 1 to npw
are for spin-up plane waves, coefficients npwx+1 to npwx+npw are for
spin-down plane waves. Scalar products are summed over the two sets.

Paolo
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Paolo Giannozzi, Democritos and University of Udine, Italy