Thank you very much for your kindly reply.

I think that one of the relevant routines for calculation of the independent-particle polarisability matrix is scatter_Bamp.F in wf_and_fft directory. (I refer to yambo-4.0.1-rev89)

Additionally, in mod_collision.F in modules directory, WF_symm_i(o) is defined as WF_symm_i(o)(fft_size,n_spinor)

Looking at the subroutine scatterBamp, Yambo seems to only consider up-up and down-down components in calculation of the polarisability matrix, that is, 1-1 and 2-2, in 2-spinor wave function. I marked these parts with the symbol, "<---".

- Code: Select all
`#if defined _FFTQE && !defined _USE_3D_FFT `

!

! add one extra conjg since FFTQE cannot account for the conjg in one go

!

!$omp parallel default(shared), private(ir)

!$omp do

do ir = 1, fft_size

isc%rho_tw_rs(ir) = isc%WF_symm_i(ir,1)*conjg(isc%WF_symm_o(ir,1)) <---

enddo

!$omp end do

!

if (n_spinor==2) then

!$omp do

do ir = 1, fft_size

isc%rho_tw_rs(ir) = isc%rho_tw_rs(ir)+isc%WF_symm_i(ir,2)*conjg(isc%WF_symm_o(ir,2)) <---

enddo

!$omp end do

endif

!$omp end parallel

As can be seen in the PRB paper, they consider off-diagonal components of 2-spinor wave function as well. That is, in Eq. (4) in PRB paper, the pairs of alpha and beta (spinor indices) include up-up, down-down, up-down, down-up. That is, Green function is in the spin basis 2x2 matrix as proposed in the earlier paper (

http://journals.aps.org/prl/abstract/10 ... 100.116402).

This is what I think the difference is.

Sincerely,

Dr. Hyungjun Lee

Institute of Theoretical Physics, EPFL