[Wien] Why dielectric function differs by 1 ?

[Rocquefelte]

Dear Liu,

It is related to the Kramers-Kro"nig relation.
Looking at these equations you will see that eps2 is an additive
quantity, while for eps1 you should consider (eps1 - 1) ...

Regards

Xavier



On 06/30/2011 07:47 PM, gbliu wrote:
> Dear all,
>
> I calculated the dielectric function of fcc Au, using a k-mesh
> 15x15x15. After the scf run, my step is as follow:
> 1. x opitc
> 2. Calculate intraband contribution, by setting swith 6 in
> fccAu.injoint file. Then I run "x joint".
> 3. Read the file fccAu.outputjoint, and get the plasma frequencies:
> 9.0075eV for both xx and zz.
> 4. Save a copy of fccAu.joint as *Intra.epsilon*, in which is the data
> of dielectric function from intraband contribution (Drude model).
> 5. Change the swith in fccAu.injoint from 6 to 4. "x joint" to compute
> epsilon.
> 6. "add intraband" set to 0 in fccAu.inkram, then "x kram", save the
> file fccAu.epsilon as *noIntra.epsilon*
> 7. "add intraband" set to 1 in fccAu.inkram, then "x kram" again, save
> the file fccAu.epsilon as *withIntra.epsilon*.
> 8. Then I compare the data in files Intra.epsilon, noIntra.epsilon and
> withIntra.epsilon, I found that:
> Im(withIntra.epsilon) = Im(noIntra.epsilon) + Im(Intra.epsilon)
> But Re(withIntra.epsilon) = Re(noIntra.epsilon) + Re(Intra.epsilon) - 1
>
> So I'm confused why not "Re(withIntra.epsilon) = Re(noIntra.epsilon) +
> Re(Intra.epsilon)" ?
> How does the difference "1" come from?
>
> Can anyone help me ?
>
> Thanks in advance.
>
> -fccAu.inop---
> 9 1 number of k-points, first k-point
> -5.0 3.0  Emin, Emax for matrix elements, NBvalMAX
> 2 number of choices (columns in *outmat): 2: hex or tetrag. case
> 1 Re xx
> 3 Re zz
> OFF ON/OFF writes MME to unit 4
> --
>
> ---fccAu.injoint--
> 1   : LOWER,UPPER and (optional) UPPER-VAL BANDINDEX
> 0. 0.00100 1. : EMIN DE EMAX FOR ENERGYGRID IN ryd
> eV : output units eV / ryd / cm-1
> *4 * *"first I use 6, then 4" * : SWITCH
> 2 : NUMBER OF COLUMNS
> 0.1 0.1 : BROADENING (FOR DRUDE MODEL - switch 6,7 - ONLY)
> --
>
> ---fccAu.inkram-
> 0.1 Gamma: broadening of interband spectrum
> 0.0 energy shift (scissors operator)
> *1 "first I use 0, then 1" * add intraband contributions? yes/no: 1/0
> 9.0075 9.0075 plasma frequencies (from joint, opt 6)
> 0.10 0.10 Gammas for Drude terms
> --
> -- 
> Best regards!
>
>  Liu Guibin
>  Postdoctoral Fellow,
>  Department of Physics,
>  The University of Hong Kong
>  
>
>
> ___
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien

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[Wien] Slab calculation for FeS2

[alpa dashora]

Dear Wien2k Users,



I am trying to perform slab calculation of FeS2 in (0 0 1) direction. I have
used a= 10.2347 bohr and vacuum=25 bohr. The value of c, taken by the
program, is 86.4035 bohr (=3*10.2347+25+3*10.2347). I would like to ask some
question about the structure file (as enclosed):



   1. How the thickness of slab will be decided?
   2. How many layers will be considered in the present structure file?
   3. How many layers will be sufficient to perform the calculation?
   4. Substitution of other atom (say Si) at Atom No. 11 and 14 can be
   considered as substrate for the slab?

Thanking you,

 --
Alpa Dashora
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