[Smeagol-discuss] Get excess charge in calculating transport

Ivan Rungger runggeri at tcd.ie
Thu Apr 23 11:55:15 IST 2009


Hello Yoshida,

   for the Hartree potential: you should always set HartreeLeadsLeft 0 
Ang, and also HartreeLeadsRight 0, and then use the value of the 
potential at 0 (I also attach a slightly modified version of the 
potential program that plots also the value at 0). That usually gives 
the best potential (there are very few cases where you would want to 
match somewhere different from 0).

Regarding the charging: what is the charge supposed to be for the 
neutral system?

Cheers,

 Ivan


Yo Yosida wrote:
> Dear all,
>  
> I calculated electrical transport with using smeagol, and I have some 
> questions:
>  
>         1. I plotted Hartree potential but the position of atoms in 
> ".VH.dat" file. is not exactly matched to position of input file.
>           Here, I cut some value, and minima value is -6.04254675 at 
> 0.749 A.
>              0.125         -2.76564980         -2.76564980
>              0.250         -3.22005486         -3.22005486
>              0.374         -4.10838985         -4.10838985
>              0.499         -5.15046215         -5.15046215
>              0.624         -5.91348267       &n bsp; -5.91348267
>              0.749         -6.04254675         -6.04254675
>              0.874         -5.47675657         -5.47675657
>
>         But my input file of lead calculation is:
>   
>              2.725487        -0.263078       0.706532        1
>              4.129771        -0.481403       0.706862        1
>              6.355842        1.109917        0.706955        1
>              1.05657 1.918837        0.707839        1
>              6.517771      &n bsp; 2.533576        0.708485        1
>              1.301313        3.324793        0.709705        1
>              4.952666        4.794172        0.710782        1
>              3.535386        4.915221        0.711375        1
>              6.369938        3.232784        1.957838& nbsp;       1
>              5.991128        0.471383        1.95892 1
>  
>    So, I set HartreesLeadLeft  0.706532 A  and HartreeLeadsBottom 
> -6.04254675. Is it true because it's not exactly match for atomic 
> position.
>  
>          2 When calculating transmission coefficient, it's converged, 
> but I have excess charge. In tutorial you have explained about losing 
> of charge. 
>  
> Could  you please suggest me for getting excess charge? Probably it's 
> due to matching of potential, but I don't know which value I should use?
>  
> negf:      1  561.56147    0.00000    0.00190 Ry
> negf:      2  565.94141    0.00000    0.00190 Ry
> negf:      3  563.57166    0.00000    0.00190 Ry
> negf:      4  564.81056    0.00000    0.00190 Ry
> negf:      2  565.94141    0.00000    0.00190 Ry
> negf:      5  565.20682    0.00000    0.00190 Ry
> negf:      3  563.57166    0.00000    0.00190 Ry
> negf:      6  565.92848    0.00000    0.00190 Ry
> negf:      4  564.81056    0.00000  &nb sp; 0.00190 Ry
> negf:      7  566.60723    0.00000    0.00190 Ry
> negf:      8  566.54834    0.00000    0.00190 Ry
> negf:      5  565.20682    0.00000    0.00190 Ry
> negf:      9  564.85081    0.00000    0.00190 Ry
> negf:     10  565.59496    0.00000    0.00190 Ry
> negf:      6  565.92848    0.00000    0.00190 Ry
> negf:     11  565.72296    0.00000    0.00190 Ry
> negf:      7  566.60724    0.00000    0.00190 Ry
> negf:     12  565.43617    0.00000   ;  0.00190 Ry
> negf:      8  566.54834    0.00000    0.00190 Ry
> negf:     13  565.40356    0.00000    0.00190 Ry
> negf:     14  565.44246    0.00000    0.00190 Ry
> negf:      9  564.85082    0.00000    0.00190 Ry
> negf:     15  565.44289    0.00000    0.00190 Ry
> negf:     16  565.43782    0.00000    0.00190 Ry
> negf:     17  565.44228    0.00000    0.00190 Ry
> negf:     18  565.44183    0.00000    0.00190 Ry
> negf:     19  565.43878    0.00000    0.00190 Ry
> negf:     20  565.43718    0.00000    0.00190 Ry
> negf:     21  565.43824    0.00000    0.00190 Ry
> negf:     22  565.43738    0.00000    0.00190 Ry
> negf:     23  565.43646    0.00000    0.00190 Ry
> negf:     24  565.43637    0.00000    0.00190 Ry
> negf:     25  565.43625    0.00000    0.00190 Ry
> negf:     26  565.43631    0.00000    0.00190 Ry
> negf:     27  565.43633    0.00000    0.00190 Ry
> negf:     28  565.43628    0.00000    0.00190 Ry
> negf:  &nb sp;  29  565.43628    0.00000    0.00190 Ry
> negf:     30  565.43623    0.00000    0.00190 Ry
> negf:     31  565.43621    0.00000    0.00190 Ry
> negf:     32  565.43621    0.00000    0.00190 Ry
> negf:     33  565.43622    0.00000    0.00190 Ry
> negf:     34  565.43621    0.00000    0.00190 Ry
> negf:     35  565.43620    0.00000    0.00190 Ry
> negf:     36  565.43620    0.00000    0.00190 Ry
> negf:      1  565.43620    0.00000    0.00190 Ry
> negf:      2&nbs p; 565.43621    0.00000    0.00190 Ry
>
> Thank you very much.
> Best regards,
>  
> Yosida
>
>
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-- 
=================================================
Ivan Rungger,

School of Physics and CRANN,  
Trinity College Dublin,  
Dublin 2,  IRELAND  
Phone: +353-1-8968454  
Email: runggeri at tcd.ie
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