Dear Nam
If you forget the DFT problem of unbound electrons in anions (which is
not a chemical or physical problem) and think about the chemistry,
there is no real process that ends with a nitrate anion in gas phase,
AFAIK. Desorption may rather involve a neutral NO2 molecule, depending
on the surface redox chemistry. Of course release of anions in
solution is possible, but you should simulate a (proper or implicit)
solvation environment.
HTH
Giuseppe
Quoting Stefano Baroni <[email protected]>:
If the anion stays charged, which is an issue by itself in DFT, the
distance will never be large enough, because the slab will generate
a macroscopic electric field. sb
___
Stefano Baroni, Trieste -- http://stefano.baroni.me
On 23 Feb 2021, at 07:05, Nam Tran <[email protected]> wrote:
Dear QE users,
I would like to calculate the adsorption energy of a negative anion
NO3- with a positive slab (The total system is neutral). I cannot
use the convention formula Eds = E(slab+anion) - E(slab) - E(anion)
because of the charge compensation when calculating the energy of
charged slab and charge adsorbate.
As the total system (slab+anion) is neutral, I wonder if it is
possible to just move the molecule far away from the slab (make
sure that vacuum in z-direction is large enough), and calculate the
energy difference i.e., one of them the molecule is far away from
the surface and in the other one the molecule adsorbed on the
surface.
Best regards
Nam
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
Via Salaria Km 29,300 - C.P. 10
I-00015 - Monterotondo Scalo (RM)
Mob (*preferred*) +39 373 7305625
Tel + 39 06 90672342 - Fax +39 06 90672316
E-mail: <[email protected]>
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
