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Number of electrons are rarely (if ever) used. In principle sum of  
the coefficients of gaussians should be equal to the number of  
electrons.

Ions from nonions are distinguished by just addition charge on the  
element column. Example:

ATOM   4175 CL    CL I   1       5.299  23.521  60.812  1.00  
18.77          CL
ATOM   4175 CL    CL I   1       5.299  23.521  60.812  1.00  
18.77          CL-1
ATOM   3854  O   THR B 220     -16.228  28.954  11.993  1.00   
7.54           O


Garib

On 4 Sep 2007, at 23:54, Mark Mayer wrote:

> Dear All,
>
> We have a structure under refinement with a putative Li bound to a  
> potentially important
> allosteric site. I'd assumed that Li+ would lose an electron and  
> have weaker scattering
> than Li Metal, but the entry for atomsf.lib has the same # of  
> electrons for both entries
> while the entries for F and F-, Na and Na+  etc all differ by ±1 as  
> expected. Since
> the coefficients for the scattering factor calculation are  
> different for Li and Li+,
> I guess four crystallographic calculations that's all that matters?
>
> Li
>          3         3        0.037700
>         1.128200        0.750800        0.617500        0.465300
>         3.954600        1.052400       85.390503      168.261002
>         0.001000        0.000000        0.000000        0.000000
> Li+1
>          3         3        0.016700
>         0.696800        0.788800        0.341400        0.156300
>         4.623700        1.955700        0.631600       10.095300
>         0.001000        0.000000        0.000000        0.000000
>
> I also have a general question about how ions are differentiated  
> from the unionized atomic species
> in the PDB. Is the left shift by 1 character in column 3 and the  
> last column, using Cl as an example
> below, how the PDB (and Refmac) distinguish Cl-1 from Cl?
>
> ATOM   4175 CL    CL I   1       5.299  23.521  60.812  1.00  
> 18.77          CL
> ATOM   3854  O   THR B 220     -16.228  28.954  11.993  1.00   
> 7.54           O
>
> Thanks for your input - Mark
>
>