[Wannier] system size limits for the transport calculation with Wannier90

[Mostofi, Arash]

Dear Farideh,

There are several points at which limitations may apply:

+ The underlying electronic structure calculation: a 500 atom DFT simulation would need significant computational resources

+ Generating the Wannier function basis: for transport calculations you would most likely want to use the disentanglement algorithms to obtain an atom-centred WF basis; for a 500 atom system I expect that this would need some careful thought and effort to do successfully (see my earlier post about projections and energy windows)

+ Computing the quantum conductance: the matrix operations (in particular the matrix inversions) in the Landauer transport code are not parallelised yet so the amount of memory attached to your processor will determine whether this is possible. A 500 atom “conductor” region, assuming 4 Wannier functions per atom, would give you a 2,000 x 2,000 matrix to be inverted for example.

Best wishes,

Arash

—
Arash Mostofi — www.mostofigroup.org<http://www.mostofigroup.org>
Director, CDT in Theory and Simulation of Materials
Imperial College London



On 5 Apr 2017, at 14:08, Faride Hajiheidari <hajiheidari.faride at gmail.com<mailto:hajiheidari.faride at gmail.com>> wrote:

Dear all,

I would like to start the transport calculations with Wannier90. My systems are double-walled carbon nanotubes (DWCNTs) with the maximum 500 atoms per unit cell.
My question is if there is a limit size for the system that can be studied by Wannier90 approach in the most efficient way.


Many thanks in advance,
Farideh



---------------------------------
Farideh Hajiheidari
RWTH Aachen University
Institute for theoretical solid state physics

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