[Pw_forum] Workfunction in STM calculation

[Gabriele Sclauzero]

Dear Andrei,

    you are right, the work function is computed, but never used in the current Tersoff-Hamann STM implementation.
By digging in the old versions of the code, I've found that the work function was needed by a wave function-extrapolation procedure used to improve the images.
That feature has been removed at some point, while the call to work_function has been left there.
The additional call is harmful, however if you want to compute images of very large systems it might create problems of too large memory requirements.
If you encounter this problem, I think you can safely comment out that call.


HTH

GS

> Is workfunction used in the STM calculation in the current version of
> Quantum ESPRESSO?
> 
> In file stm.f90 there is a comment that says that the routine needs
> workfunction wf. But it looks like the variable wf is not really used
> inside the subroutine stm(), except that it gets overwritten at the very
> end by the number of states (istates).
> 
> On the other hand, during STM postprocessing step, before stm() the
> subroutine work_function(wf) is called, which creates the file
> seedname.workf. Is this file used at some later point in creating the STM
> image?
> 
> Thank you,
> 
> Andrei Malashevich
> --
> Postdoctoral Associate
> Department of Applied Physics
> Yale University
> 
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§ Gabriele Sclauzero, EPFL SB ITP CSEA
   PH H2 462, Station 3, CH-1015 Lausanne