[CP2K-user] [CP2K:12268] Binding energy with charged unit cell

[hut... at chem.uzh.ch]

Forgot: If the system is charged, you get a neutralizing background
charge for periodic systems. This leads to slow convergence of
binding energies.

Juerg Hutter
--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie C                FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: cp... at googlegroups.com
From: hut... at chem.uzh.ch
Sent by: cp... at googlegroups.com
Date: 09/25/2019 12:18PM
Subject: Re: [CP2K:12268] Binding energy with charged unit cell

Hi

your problem is equivalent to the problem of calculating 
charged defect energies in solids. There is a huge literature
on how to solve the problems related to periodic boundary
conditions. See for example the papers by Alfredo Pasquarello.

regards

Juerg Hutter
--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie C                FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: "cp2k" <cp... at googlegroups.com>
From: "LK" 
Sent by: cp... at googlegroups.com
Date: 09/23/2019 10:32PM
Subject: [CP2K:12258] Binding energy with charged unit cell

Hello All,

I'm trying to calculate the binding energy of an ion inside a condensed phase unit cell.

The energy difference equals the energy of the full (neutral) liquid system minus the energy of two oppositely charged systems: vacuum-phase molecule (in this case, negatively charged) and liquid/hole combo (positively charged). 

Simply setting the CHARGE setting in my input file leads to spurious results, especially large dependence on vacuum-phase ion's energy on the unit cell size. 

I've been playing around with turning the liquid unit cell into a cluster, and trying to calculate the energy without periodicity, i.e. using WAVELET poisson with ANALYTIC solver. But I'm not sure whether this plays nice with the CHARGE keyword. 

Maybe a better way would be to stay within periodic boundary conditions, but turn on MULTIPOLE poisson method...again, not sure how this plays with having a charged unit cell. 

I can't find in the documentation what exactly setting a nonzero CHARGE does... does it do nothing, or does it automatically turn on a background jellium?

Any suggestions would be greatly appreciated. 

Thanks,

L.K.



  
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