[Pw_forum] Image charge interaction
giuseppe.mattioli at ism.cnr.it
Tue Sep 13 17:19:10 CEST 2016
I've used a semiempirical U value of 4 eV on the Cl 3p electrons to
keep together the electrons of Cl- in photosystem II. However the ion
was also screened by a few ligands and by the ENVIRON dielectric
medium. Notwithstanding DFT+U and a well-shaped ENVIRON dielectric can
be both of help in your system.
Quoting Thomas Brumme <thomas.brumme at mpsd.mpg.de>:
> Hi Ilya,
> I wonder if the SIC implementation in CP can help:
> Unfortunately, I'm not familiar with CP...
> On 09/13/2016 03:44 PM, Ilya Ryabinkin wrote:
>>> If I understand this correctly, it seems a less satisfactory answer that
>> just having the uniform jellium background?
>> No. In particular, I have Cl- species in my system, but there is no
>> way in common GGAs to keep an electron on chlorine -- due to self
>> interaction the electron is too weakly bound (if any) to Cl and DFT
>> gives a completely wrong, de-localized solution for an extra electron.
>> Neutralizing background will simply eat up the field of this
>> delocalized electron and I'll be simulating a system which resembles
>> more a *neutral* Cl atom on a slab rather than an anion.
>> One of the possible ways to work around -- is to devise a
>> pseudopotential for Cl with the configuration [He] 2s^2 2p^5 3s^2
>> 3p^6, which has a hole in 2p and an extra electron in 3p, then "bury"
>> the hole inside a pseudopotential... This solution, however, leads to
>> the apparent lack of charge-image interaction since the resulting
>> pseudoatom is neutral (in fact, it looks like Ar).
>>> the state of charge of your particle
>>> will be determined by the physics - i.e. the xc functional will decide
>>> how much charge should sit on the particle
>> I wish it could be true... but not for the common DFA-s
>>> Which capability? Adding an empirical extra term in the forces for
>>> the charge?
>> Yes. I'm wondering if some one already did this. I can do it myself,
>> but for the sake of not re-inventing the wheel...
>> On Tue, Sep 13, 2016 at 6:26 AM, Lorenzo Paulatto
>> <lorenzo.paulatto at impmc.upmc.fr> wrote:
>>> it is not too clear to me what you need, but is something like
>>> this: http://
>>> journals.aps.org/prb/abstract/10.1103/PhysRevB.89.245406 ?
>>> It is implemented in the upcoming version 6.0 of QE,
>>> The feature is still disabled in the downloadable beta versione, but it is
>>> enabled in the last daily snapshots at http://qe-forge.org/snapshots/ (no
>>> guarantee anything works).
>>> On Monday, 12 September 2016 18:13:25 CEST Ilya Ryabinkin wrote:
>>>> Dear colleagues:
>>>> I am simulating dynamics of a charged particle on a metallic slab. To
>>>> avoid difficulties with Coulomb energy of a charged cell, we use a
>>>> core-hole trick to introduce a compensatory positive charge directly
>>>> into a particle. However, the image-charge interaction is clearly
>>>> absent and we would like to bring it back.
>>>> Did anyone bother him/herslef to implement is in QE? I know VASP has
>>>> this capability, but it is out of scope.
>>>> Thanks in advance,
>>> Dr. Lorenzo Paulatto
>>> IdR @ IMPMC -- CNRS & Université Paris 6
>>> +33 (0)1 44 275 084 / skype: paulatz
>>> 23-24/4é16 Boîte courrier 115,
>>> 4 place Jussieu 75252 Paris Cédex 05
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
> Dr. rer. nat. Thomas Brumme
> Max Planck Institute for the Structure and Dynamics of Matter
> Luruper Chaussee 149
> 22761 Hamburg
> Tel: +49 (0)40 8998 6557
> email: Thomas.Brumme at mpsd.mpg.de
> Pw_forum mailing list
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