[Pw_forum] Interacting ions

[Giuseppe Mattioli]

Dear Valentina

> perform an energy calculation

What are you trying to do exactly? Are you calculating the interaction energy of the two ions or are you interested in the properties of the "salt"?
Anyway, the results will strongly depend on the flavour of DFT employed in the calculation. It is possible that if you use a (e.g.) B3LYP framework 
your fragments in a same supercell are "compensated" like a semiconductor, and show the expected charge. But you probably will not obtain a good 
dissociation curve. Of course, if you are not planning to study the interaction of your fragments with, e.g., a surface, you may find more comfortable 
and time-saving to use some quantum chemistry program which performs multi-reference calculations.

HTH
Giuseppe

On Friday 30 May 2014 11:25:10 Valentina Cantatore wrote:
> Hi everyone,
> 
> I'm a fresh new QE espresso user. I write you to ask if there is any way to
> perform an energy calculation between two interacting ions (CH3NH3+
> PbI3-). In particular, how can I specify the charges of my two fragments?
> 
> Thank you very much in advance for your answers.
> 
> Valentina Cantatore
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum


********************************************************
- Article premier - Les hommes naissent et demeurent
libres et ègaux en droits. Les distinctions sociales
ne peuvent être fondèes que sur l'utilitè commune
- Article 2 - Le but de toute association politique
est la conservation des droits naturels et 
imprescriptibles de l'homme. Ces droits sont la libertè,
la propriètè, la sùretè et la rèsistance à l'oppression.
********************************************************

   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
   v. Salaria Km 29,300 - C.P. 10                
   I 00015 - Monterotondo Stazione (RM)          
   Tel + 39 06 90672836 - Fax +39 06 90672316    
   E-mail: <giuseppe.mattioli at ism.cnr.it>
   http://www.ism.cnr.it/english/staff/mattiolig
   ResearcherID: F-6308-2012