Yambo Community Forum

Hello!

I'm new to Yambo, and I'm interested to apply the code to calculations of photoluminescence in rare-earth doped compounds. I'm specifically interested not in energies or band gaps but in the total charge density distribution in the simulation cell associated with localized and delocalized excited states. Can Yambo calculate these distributions, and if so, what parts of the code should I be using? I would be very grateful if someone could point me in the right direction.

Many thanks in advance,
Steve Kirk

Dr. Steven Kirk (steven.kirk@cantab.net)
Dept. of Chemistry and Chemical Engineering
Hunan Normal University
Changsha 410081 HUNAN
People's Republic of China

Hello again!

OK, I have checked out some of the tutorial material for 'ypp' and seen that it can output charge densities in XcrysDen .xsf format. My application relies on taking spatial derivatives of charge densities, which I would prefer to do directly from wavefunction data rather than have to approximate the spatial derivatives using a finite-difference approach. Can anyone give me any clues where to look for documentation on output formats for excited-state wavefunctions?

Thanks for any help and advice you can provide!

Steve Kirk

Dear Steve,

first of all welcome onboard! Then, regarding your problem there is no problem in calculating the density derivative directly from the wavefunctions. But first let me better understand what your are searching for. You write:

srkirk wrote: I'm specifically interested not in energies or band gaps but in the total charge density distribution in the simulation cell associated with localized and delocalized excited states.

What "type" of excited states do you have in mind ? Electrons excited in empty states, excitons ? With ypp you can plot the DFT electronic density, that is a ground state quantity. Excited electrons, as far as I know, can be simulated using constrained DFT. Excitonic wavefunctions, instead, can be computed using yambo+ypp. But in this case this has nothing to do with a charge density as it represents the wavefunction of the electron-hole pairs emobodied in the excitonic state.

So, we can surely help you in finding the tool/routine to change in Yambo, but first we need to define properly the observable you want to plot/calculate.

Andrea

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