[Pw_forum] About nelec and tot_charge

Axel Kohlmeyer akohlmey at cmm.chem.upenn.edu
Thu Dec 6 14:51:20 CET 2007

On Thu, 6 Dec 2007, oulihui666 wrote:

dear lihui ou,

LO> Dear pwscf users, I want to do a structural relaxation of a charged 
LO> system using pwscf. For example, In the process of oxygen reduction 
LO> reaction, adsorption of hydration proton(H3O+) on Pt(111) surface, 
LO> simultaneously, a extra electron is added, that is to say, O2 + H+ + 
LO> e- . When I calculate this system with pwscf, could I add charge and 
LO> add a electron simultanously?  I will be glad to learn some extra 

there is no difference between changing the total charge and
adding an electron. those two parameters in the input are 
connected and you'll get an error message if they are not

LO> tricks related to fast scf convergence in such scenarios.  Thanks in 

charged systems, particularly with excess electrons 
can indeed be tricky to converge. there are a lot of
hints in the quantum espresso website and in the mailing
list archive. which of those may apply or not to your
system is difficult to predict. getting fast convergence
is a bit of a craft based on empirical knowledge, i.e.
there is no alternative to practicing and experimenting
to learn the "tricks of the trade".


LO> advance Lihui Ou

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

Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
If you make something idiot-proof, the universe creates a better idiot.

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