Imag Dielectric function of gold not matching with experimental (RPA)

[Daniele Varsano]

Dear Hasan,

it seems you have a rather good agreement with experiments.

the damping is an artificial parameter that it is introduced to mimic the peak broadening of the experiments (related to the lifetime).
It is a common procedure to adjust it with the experiment you want to compare with.
Lower damping needs larger k points grid to have a smooth behaviour, the number of k points and the dampoing are somehow related as the smearing in a DFT calculation.

I do not if it can be useful for your case you can also consider a non-constant smearing providing considering something like:

Code: Select all

% DmRngeXd
 0.0100000 | 0.100000 |         eV    # [Xd] Damping range
%

Yambo will apply a smearing that increase linearly from 0.01 to 0.1 in the energy range you provided.

Best,

Daniele

[muhammadhasan]

Hi Professor,

Thank you so much. I will run it again considering non constant damping. However, what might be the reason that imag epsilon is matching, but real epsilon is not matched?. Isn't it Kramers-kronig relation that can find out real epsilon if we provide imag epsilon?

Best
Md J Hasan
PhD Student
Mechanical Engineering
University of Maine

[Daniele Varsano]

Dear Md J Hasan,

yes, Im and Re are related by KK relations but note that they can have different convergence parameter, Real part converge slowly with respect the energy range, or if you want the transitions included in the calculation.

Best,
Daniele

[muhammadhasan]

Hi Professor,

When you mentioned that "they can have different convergence parameters," does it mean they can have different BndsRnXd (Polarization function bands), which might differ from what is used in the imaginary case (as follows)? Or does it refer to some other specific parameter?

Code: Select all

optics                           # [R] Linear Response optical properties
infver                           # [R] Input file variables verbosity
chi                              # [R][CHI] Dyson equation for Chi.
dipoles                          # [R] Oscillator strenghts (or dipoles)
ElecTemp= 0.0388         eV    # Electronic Temperature
FFTGvecs= 20            Ry    # [FFT] Plane-waves
Chimod= "IP"                     # [X] IP/Hartree/ALDA/LRC/PF/BSfxc
% QpntsRXd
     1 |  1 |                     # [Xd] Transferred momenta
%
% BndsRnXd
    245 |  267  |
%
% EnRngeXd
  0.00000 | 1.00000 |         eV    # [Xd] Energy range
%
% DmRngeXd
 0.0220000 | 0.0220000 |         eV    # [Xd] Damping range
%
ETStpsXd= 50                   # [Xd] Total Energy steps
DrudeWXd= ( 7.900000 , 0.05500 )  eV    # [Xd] Drude plasmon
% LongDrXd
 1.000000 | 0.000000 | 0.000000 |        # [Xd] [cc] Electric Field

Thank you

Best
Md J Hasan
PhD Student
Mechanical Engineering
University of Maine

[Daniele Varsano]

Dear Md J Hasan,

correct, different number of bands.

Best,

Daniele