[ase-users] about charged slab calculation

[John Kitchin]

no idea. I have never used that part of the code.
John

-----------------------------------
John Kitchin
Assistant Professor
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
http://kitchingroup.cheme.cmu.edu





On Thu, Feb 24, 2011 at 10:04 AM, Huang Bing <hbdft2008 at gmail.com> wrote:
> 2011/2/24 John Kitchin <jkitchin at andrew.cmu.edu>
>>maybe you could use something like this:
>>2011/2/24 John Kitchin <jkitchin at andrew.cmu.edu>
>>maybe you could use something like this:
>>http://gilgamesh.cheme.cmu.edu/jacapo/jacapo/3-surfaces/3.9-external-potential/3.9.0-external-potentials.html
>>to setup an external dipole field that decouples the cells.?
> These two kinds of calculation may be correlated strongly, but
> one cannot figure out the equivalent dipole induced by an extra
> charge.
>>in the old ASE2 code there was this possibility.
>>SetElectrostaticDecoupling(numberofgaussians=3,ecutoff=100):
>>   Add electrostatic decoupling (Jan Rossmeisl). Decoupling activates
>>the three dimensional electrostatic decoupling. Based on paper by
>>Peter E. Bloechl: JCP 103 page7422 (1995).
>>I don't think this is currently implemented in Jacapo, but it could be
>>done. you just need to setup the right netcdf variables to tell the
>>fortran code what to do i think.
> The option SetElectrostaticDecoupling(numberofgaussians=3,ecutoff=100)
> does exist in the old DACAPO code and I've ran some simple charged slab
> calculation (Pt(111) (1x1) with 8 atomic layers; extra charge: 0.01)
> a moment ago. But I found a strange thing: the dE/dN is extraodinarily
> large and the output charge resides in each slab layer oscillates, and the
> amount of charge is not small, suggesting that the pure Pt(111) surface
> has an ionic structure, of course this is not true. any idea?
>
> 2011/2/24 John Kitchin <jkitchin at andrew.cmu.edu>
>>
>> maybe you could use something like this:
>>
>>
>> http://gilgamesh.cheme.cmu.edu/jacapo/jacapo/3-surfaces/3.9-external-potential/3.9.0-external-potentials.html
>>
>> to setup an external dipole field that decouples the cells.?
>>
>>
>> in the old ASE2 code there was this possibility.
>>
>> SetElectrostaticDecoupling(numberofgaussians=3,ecutoff=100):
>>    Add electrostatic decoupling (Jan Rossmeisl). Decoupling activates
>> the three dimensional electrostatic decoupling. Based on paper by
>> Peter E. Bloechl: JCP 103 page7422 (1995).
>>
>> I don't think this is currently implemented in Jacapo, but it could be
>> done. you just need to setup the right netcdf variables to tell the
>> fortran code what to do i think.
>>
>> j
>>
>>
>> John
>>
>> -----------------------------------
>> John Kitchin
>> Assistant Professor
>> Doherty Hall A207F
>> Department of Chemical Engineering
>> Carnegie Mellon University
>> Pittsburgh, PA 15213
>> 412-268-7803
>> http://kitchingroup.cheme.cmu.edu
>>
>>
>>
>>
>>
>> On Wed, Feb 23, 2011 at 10:58 PM, Duy Le <ttduyle at gmail.com> wrote:
>> > It is not about the code. It is about theory. Do you know any theory
>> > that helps you correct the total energy of the charge system whose
>> > supercell is NOT Cubic (needed for slab model)?
>> >
>> > --------------------------------------------------
>> > Duy Le
>> > PhD Student
>> > Department of Physics
>> > University of Central Florida.
>> >
>> > "Men don't need hand to do things"
>> >
>> >
>> >
>> > On Wed, Feb 23, 2011 at 10:33 PM, Huang Bing <hbdft2008 at gmail.com>
>> > wrote:
>> >> They say that it's not possible to do charged slab calculation in vasp,
>> >> so i wonder if these kind of calculation is valid or not in Dacapo.
>> >> see this url
>> >> http://cms.mpi.univie.ac.at/vasp-forum/forum_viewtopic.php?4.2463
>> >> for detail, or have a look at the text below, which is copied directly
>> >> from the contents in that link:
>> >>>I have a question. Is it possible to optimize charged unit cell, for
>> >>> example,
>> >>>if I want to investigate adsorption of charged species on neutral
>> >>> surface?
>> >>>If yes, where can I read about method, possible errors, etc?
>> >>>Thank you in advance.
>> >> Here is the admin's reply:
>> >> a) on charged systems in general, please have a look in the manual
>> >>     (chapter multipole corrections)
>> >> b) Actually, you MUST NOT set the number of electrons manually for
>> >>     a slab calculation. I.e., when you calculate the surface+adsorbate
>> >>    system, you are not allowed to select a specific charge state for
>> >> the
>> >>    adsorbate by increasing the number of electrons manually. Specific
>> >>    charge state calculations make sense only in 3d systems and for
>> >>    cluster calculations.  The electrostatic energy of such a slab is
>> >>     however only conditionally convergent and in practice even infinite
>> >>     (BASIC, BASIC ELECTROSTATICS).
>> >>    Only if the calcuations are done properly, i.e., if your slab is
>> >> large
>> >>    enough and the lateral dimension (x,y) of your surface is large
>> >> enough
>> >>     (test for the necessary 2D dimension, the total energy has to
>> >> converge
>> >>     to the correct value with (1/(distance between the charged species)
>> >> )
>> >>    the energy should converge to the proper value, i.e. the adsorbed
>> >> species
>> >>  should acquire the correct charge state (then, it is acquired
>> >> automatically).
>> >> Any comments is highly appreciated!
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>> >>
>> >
>
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