[Pw_forum] About background charge

[oulihui666]

Dear All,
In my calculated systems, which carry a positive charge, at the same time, background charges with same amount is added to all unit
cell include vacuum layer automatically, but in my systems, I don't want to let vacuum layer fill backgroun charges when calculated. 
Thus, I'd like to ask if PWSCF can do calculations that vacuum layer do not fill backgrount charges ?  
I have checked the manual and original pipemails, but didn't find many topics on background charges.
However,I found many discussions on EXTERNAL POTENTIAL which makes it possible to add an external 
electrostatic field.  
If possible, how ? 
 
Many thanks.
Best regards,
Lihui Ou


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Lihui Ou
PH.D Candidate in Electrochemistry                      
College of Chemistry and Molecular Science            
Wuhan University,430072,Hubei Province,China 
E-mail:oulihui666 at 126.com
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