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[Xavier Gonze <gonze@pcpm.ucl.ac.be>]

Dear Yu Chol Jun,

Sorry, I imagined that you were interested by H+  interacting with  
some neutral molecule.
Well, H+ alone has no electron at all ... The total energy is 0 Ha !

If you want nevertheless to make a calculation, take the limit  
tending to zero
of very small occupations of H, with the corresponding balancing  
"charge". Do not forget to make
a convergence study on cell size !

Xavier

On 24 May 2007, at 19:02, Yu Chol Jun wrote:

> Dear Prof. Xavier Gonze,
>
> thank you very much for your valuable trick.
>
> Xavier Gonze wrote:
> > On 23 May 2007, at 16:04, Yu Chol Jun wrote:
> > Same trick : declare the adequate number of electrons with  
> > "nband"  and "occ" , complete the charge
> > balance with "charge". Then, compute the electronic ground state.  
> > You  might get H+ , if the ground state does not put charge (or  
> > little) on your H nucleus.
>
> I already tried to calculate the total energy of H+ by using  
> 'charge = +1' in hydrgen atom, but the following error was occured
>
> > inkpts : istwfk preprocessed, gives following first values (max.  
> > 6): 2
> >  chkneu : initialized the occupation numbers for occopt=    4
> >     spin-unpolarized case :
> >   0.00
> >  chkneu: nelect_occ=  0.00000000E+00, zval=  0.50000000E-05,
> >          and input value of charge=  0.10000000000000E+01,
> >    nelec_occ is computed from occ and wtk
> >    zval is nominal charge of all nuclei, computed from zion (read  
> > in psp),
> >    charge is an input variable (usually 0).
> >  ERROR - These must obey zval-nelect_occ=charge to better than  
> > 0.10E-07
> >  This is not the case.
> >    Action : check input file for occ,wtk, and charge.
> >    Note that wtk is NOT automatically normalized when occopt=2,
> >    but IS automatically normalized otherwise.
>
> Here is the input file.
> >   ecut  30.0
> >  toldfe  1.0d-7
> >  prtgeo  1
> >  occopt  4
> >  diemac  1.0
> >  diemix  1/3
> >  isecur -2
> >   nband  1
> >     occ  0
> >  charge +1
> >     kpt  0 0 0
> >     wtk  1.0
> >   nstep  30
> >     ixc  15
> >   acell  3*14.0
> >   rprim  1.0 0.0 0.0
> >          0.0 1.0 0.0
> >          0.0 0.0 1.0
> >  ntypat  1
> >   znucl  1
> >   natom  1
> >   typat  1
> >   xcart  3*7.0
>
> Looking forward to replying.
>
> Best regards.
>
> Yu.