On 29/08/2024 12:36, Alex Kirkpatrick wrote:
Thanks for the reply Lorenzo.
I'm very new to all this but my thought was that, to have some control
over the distance between the 'electron' and the surface, I would need
to include it as a discrete entity.
Hello, QE is a code based on plane waves, which means that you cannot
choose where an electron goes. But I don't think you need to use an
explicit electron for your task. Thank to the power of numerical
simulation, you can plot/measure directly the magnitude of the Kohn-Sham
potential, (which is identical to the Hartree electrostatic potential
when you go in the vacuum).
The procedure is similar to the one explained in the workfunction
example (PP/examples/WorkFct_example) which shows how to compute the
average value of the electrostatic potential far away in the vacuum to
estimate the energy required to pull an electron from the surface out to
infinity.
Of course the procedure is not entirely self-consistent (i.e. pulling
out the electron would change the potential) but for a metal it is very
close, and if you really need to you can remove some amount of charge
fro mthe surface using a positive value for tot_charge
hth
I would then be able to vary the distance and see how things change.
Is this the wrong way to go about it?
Kind regards
Alex
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------------------------------------------------------------------------
*From:* users <[email protected]> on behalf of
Lorenzo Paulatto <[email protected]>
*Sent:* 29 August 2024 10:15
*To:* Quantum ESPRESSO users Forum <[email protected]>
*Subject:* Re: [QE-users] Pseudopotential to approximate a free electron?
You could, probably, but why not just use tot_charge=-1
Kind regards
On August 29, 2024 10:03:30 AM GMT+02:00, Alex Kirkpatrick
<[email protected]> wrote:
Dear all,
Is it possible to create a pseudopotential file, or modify an
existing one like hydrogen, to approximate placing a free electron
in the simulation cell?
The end goal being to model its interaction with material surfaces
in vacuum.
Best wishes,
Alex
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--
Dr. Lorenzo Paulatto
IdR @ IMPMC - CNRS UMR 7590 & Sorbonne Université
phone: +33 (0)1 442 79822 / skype: paulatz
http://www.impmc.upmc.fr/~paulatto/ - https://anharmonic.github.io/
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