fxc matrix elements

[sivanr]

Dear yambo developers,

I am a new user, and currently exploring your code- mainly for TDDFT applications.

I would like to observe the fxc matrix elements (within linear response), for example in your SiH4 tutorial.
Is this possible?

Many thanks, and best regards

Sivan Refaely-Abramson
PhD student
Weizmann Institute of Science, Israel.

[Daniele Varsano]

Dear Sivan,
the Fxc matrix elements are not stored in file, otherwise you will end up with an HD full very soon.
The TDDFT can be solved either in reciprocal space and in KS basis set. Depending on what implementations you are using you will have Fxc_GG' or <n|fxc|n'> matrix elements. Assuming you are interested in the latter, you can print them adding write commands in

Code: Select all

src/bse/K.F

the fxc matrix elements are calculated in tddft_alda_R_space function defined in

Code: Select all

./src/tddft/tddft_alda_r_space.F

and called here in src/bse/K.F:

Code: Select all

         if (BS_K_is_ALDA) H_res_x=H_res_x+&
&                          tddft_alda_R_space(iq,(/ic1,ic2/),(/ik1,ik2,ik1,ik2/),&
&                                                (/iv1,iv2/),(/is1,is2,is1,is2/),1)

Hope it helps.

Best,

Daniele

[sivanr]

Dear Daniele,

Thank you for your quick reply!

Can you please also comment on how to print the first option, namely Fxc_GG'?

Sivan.

[Daniele Varsano]

Dear Sivan,
the Dyson equation:
\chi=\chi^0+\chi^0(v+Fxc)\chi
is solved here:
./src/pol_function/X_s.F

and the tddft kernel is calculated here:
/src/tddft/tddft_alda_g_space.F

through the libxc libraries.

Cheers,

Daniele

[sivanr]

Thanks a lot!

Sivan

[sivanr]

Hello again,

I used to print the real-space fxc matrix elements following your instructions from above, namely from within the bse/K.F code.

However, ever since I am using the new 3.4.1 version, I am having troubles with applying it. In fact, it seems like the real-space tdlda calculation does not use the K.o binary at all.

Do the matrix-elements still being calculated using tddft_alda_r_space.F? Can you please advice me regarding where should I approach in order to write those elements?

Thanks a lot!
Sivan

[Daniele Varsano]

Dear Sivan,
please fill your signature with your affiliation.

The call to the alda kernel is still there:
./src/K.F

Code: Select all

462          ! :::ALDA        (resonant):::
463          !
464          if (BS_K_is_ALDA) H_res_x=H_res_x+&
465 &                          tddft_alda_r_space(iq,(/ic1,ic2/),(/ik1,ik2,ik1,ik2/),&
466 &                                                (/iv1,iv2/),(/is1,is2,is1,is2/),1)
467          !
468          ! :::ALDA        (coupling):::
469          !
470          if (BS_K_is_ALDA) H_cpl_x=H_cpl_x+&
471 &                          tddft_alda_r_space(iq,(/ic1,ic2/),(/ik1,ik2,ik1,ik2/),&
472 &                                                (/iv1,iv2/),(/is1,is2,is1,is2/),2)
473          !

you should add here your writing lines and recompile all.
Assure to do a make clean_all before reconfiguring and recompile the code.

Best,
Daniele