Re: [QE-users] Local charge

[Robert Molt]

Without knowing your system, it is impossible to comment on whether the 
concept of local charge exists, meaningfully. Can you specify your system?


For example, there is no such thing as a widely-accepted method to 
calculate local charge because the concept of local charge does not 
exist, rigorously. No law of physics demands that electrons are "owned" 
by a certain atom (Coulomb's law neither knows nor cares about the human 
concept of atoms). In some cases, electrons' positions happen to be 
relatively localized (like, say average organic molecules), and the term 
has more meaning. If we are talking about a highly delocalized system, 
the term has no meaning (because the electrons don't "belong" to anyone).



On 8/11/18 3:25 PM, Comer, Benjamin M wrote:


Mr. Hosseini,

I am not sure what type the local charges and magnetizations QE prints 
by default, but you should use a widely accepted method to calculate 
local charges, such as Bader analysis. I should note that there is no 
“correct” way to calculate a local charge. However, there are many 
ways to calculate charges developed by the community, each with it’s 
own drawbacks (see Wikipedia link below.) I’d recommend using Bader 
charges, DDEC6, or the lowden charges printed out from the projwfc.x 
code in the quantum espresso suite(links below.)


https://en.wikipedia.org/wiki/Partial_charge

http://theory.cm.utexas.edu/henkelman/code/bader/

https://sourceforge.net/projects/ddec/files/

http://phya.snu.ac.kr/~nmcuong/board/physics/INPUT_PROJWFC.html 



Hope it helps,

Ben Comer

Georgia Tech

>Dear All

>

>I need to compute local charge of atoms in my unit cell. As I checked, the 
output of SCF provides local charge with the corresponding 
>magnetization. The numbers are confusing. How can I compute the local 
charge?


>

>M.R.Hosseini

>Tarbiat Modares University, Department of Chemistry, Iran



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--
Dr. Robert Molt Jr.
r.molt.chemical.phys...@gmail.com

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Re: [QE-users] Local charge

[Comer, Benjamin M]

Mr. Hosseini,



I am not sure what type the local charges and magnetizations QE prints by 
default, but you should use a widely accepted method to calculate local 
charges, such as Bader analysis. I should note that there is no "correct" way 
to calculate a local charge. However, there are many ways to calculate charges 
developed by the community, each with it's own drawbacks (see Wikipedia link 
below.) I'd recommend using Bader charges, DDEC6, or the lowden charges printed 
out from the projwfc.x code in the quantum espresso suite(links below.)



https://en.wikipedia.org/wiki/Partial_charge



http://theory.cm.utexas.edu/henkelman/code/bader/

https://sourceforge.net/projects/ddec/files/

http://phya.snu.ac.kr/~nmcuong/board/physics/INPUT_PROJWFC.html



Hope it helps,

Ben Comer

Georgia Tech



>Dear All

>

>I need to compute local charge of atoms in my unit cell. As I checked, the 
>output of SCF provides local charge with the corresponding >magnetization. The 
>numbers are confusing. How can I compute the local charge?

>

>M.R.Hosseini

>Tarbiat Modares University, Department of Chemistry, Iran

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[QE-users] Local charge

[Mohammadreza Hosseini]

Dear All


I need to compute local charge of atoms in my unit cell. As I checked, the 
output of SCF provides local charge with the corresponding magnetization. The 
numbers are confusing. How can I compute the local charge?


M.R.Hosseini

Tarbiat Modares University, Department of Chemistry, Iran
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