[Pw_forum] Comparison between PWSCFand WanT?

[Andrea Ferretti]

On Tue, 10 Jan 2006 yuss at jlu.edu.cn wrote:

> Dear all:
>    I know that PWSCF can study the transport of nanostructure using PWCOND.X, 
>    but what are difference between it and WanT?
>    Thanks,
>    s.s.yu
> _______________________________________________


Hi all,

as far as I know, the two methods compute ballistic transport 
according to landauer formalism... this means that transport is directly 
related to the scattering probelm which should be solved...

while PWCOND.X performs this task by computing the complex 
band structure of the "conductor region" (in the plane-wave pseudopot 
approach of espresso), WanT adopts Marzari-Vanderbilt "maximally 
localized" Wannier functions as a localized basis set and manages a 
real-space matrix green function approach (according to the Fisher-Lee 
expression for Landauer formula)

basically WanT starts from the standard (kohn-sham) electronic structure 
as computed by espresso and performs the calculation of Waniner functions 
as well as of the KS hamiltonian representation on this basis...
At this point you are able to match the conductor region to the lead 
regions, compute lead self-energies and final evaluate the transmittance 
across the conductor..

I am sure that Andrea Dal Corso or Francesco Antoniella (and probably many 
others) can add much more detail about the pwcond.x approach...   

regards
Andrea