mirror of https://gitlab.com/QEF/q-e.git
137 lines
3.7 KiB
Fortran
137 lines
3.7 KiB
Fortran
|
subroutine build_spectrum(ampl,en,ipol)
|
||
|
|
!this subroutine builds up the absorption spectrum
|
||
|
|
!and prints it on file
|
||
|
|
|
||
|
|
USE exciton
|
||
|
|
USE io_global, ONLY : stdout,ionode
|
||
|
|
USE bse_wannier, ONLY : spectra_e_min,spectra_e_max,n_eig,spectra_nstep,spectra_broad
|
||
|
|
USE constants, ONLY : RYTOEV, PI
|
||
|
|
USE cell_base, ONLY : omega
|
||
|
|
USE io_files, ONLY : tmp_dir,prefix
|
||
|
|
|
||
|
|
implicit none
|
||
|
|
|
||
|
|
REAL(DP), INTENT(in) :: ampl(n_eig), en(n_eig)
|
||
|
|
|
||
|
|
INTEGER, EXTERNAL :: find_free_unit
|
||
|
|
|
||
|
|
REAL(DP), ALLOCATABLE :: omega_g(:),absorption(:),broad_abs(:),excdos(:)
|
||
|
|
COMPLEX(DP), ALLOCATABLE :: den(:,:),cspectrum(:),campl(:)
|
||
|
|
REAL(DP) :: eta,step,prefac,sumdos,norm
|
||
|
|
COMPLEX(DP) :: lambda_sum
|
||
|
|
INTEGER :: i,j,iun,ipol
|
||
|
|
|
||
|
|
LOGICAL :: debug
|
||
|
|
|
||
|
|
call start_clock('build_spectrum')
|
||
|
|
debug=.true.
|
||
|
|
eta=0.001
|
||
|
|
|
||
|
|
if(debug) then
|
||
|
|
if(ionode) then
|
||
|
|
do i=1,n_eig
|
||
|
|
write(stdout,*) '#',i,'E=',en(i),'A=',ampl(i)
|
||
|
|
enddo
|
||
|
|
endif
|
||
|
|
endif
|
||
|
|
|
||
|
|
allocate(omega_g(spectra_nstep))
|
||
|
|
allocate(absorption(spectra_nstep))
|
||
|
|
allocate(excdos(spectra_nstep))
|
||
|
|
allocate(broad_abs(spectra_nstep))
|
||
|
|
allocate(cspectrum(spectra_nstep))
|
||
|
|
allocate(den(spectra_nstep,n_eig))
|
||
|
|
allocate(campl(n_eig))
|
||
|
|
|
||
|
|
if (ipol==1) then
|
||
|
|
!convert energy range in Ry
|
||
|
|
spectra_e_min=spectra_e_min/RYTOEV
|
||
|
|
spectra_e_max=spectra_e_max/RYTOEV
|
||
|
|
endif
|
||
|
|
|
||
|
|
!build the omega grid
|
||
|
|
step=(spectra_e_max-spectra_e_min)/dble(spectra_nstep-1)
|
||
|
|
|
||
|
|
do i=0, spectra_nstep-1
|
||
|
|
den(i+1,1:n_eig)=dcmplx(1.d0,0.d0)/(dcmplx(en(1:n_eig),0.d0)-dcmplx(spectra_e_min+dble(i)*step,eta))
|
||
|
|
omega_g(i+1)=(spectra_e_min+dble(i)*step)*RYTOEV
|
||
|
|
enddo
|
||
|
|
|
||
|
|
!compute the absorption spectrum
|
||
|
|
campl(1:n_eig)=dcmplx(ampl(1:n_eig),0.d0)
|
||
|
|
!campl(1:n_eig)=dcmplx(1.d0,0.d0)
|
||
|
|
|
||
|
|
cspectrum(1:spectra_nstep)=(0.d0,0.d0)
|
||
|
|
|
||
|
|
call zgemm('N','N',spectra_nstep,1,n_eig,(1.d0,0.d0),den,spectra_nstep,campl,n_eig,(0.d0,0.d0),cspectrum,spectra_nstep)
|
||
|
|
|
||
|
|
prefac=8.d0*PI/omega
|
||
|
|
!prefac=1.d0
|
||
|
|
absorption(1:spectra_nstep)=prefac*aimag(cspectrum(1:spectra_nstep))
|
||
|
|
|
||
|
|
!add gaussian broadening
|
||
|
|
broad_abs(1:spectra_nstep)=0.d0
|
||
|
|
do i=1,spectra_nstep
|
||
|
|
norm=0.d0
|
||
|
|
do j=1,spectra_nstep
|
||
|
|
broad_abs(i)=broad_abs(i)+&
|
||
|
|
absorption(j)*exp(-((omega_g(i)-omega_g(j))**2)/(2.d0*spectra_broad**2))
|
||
|
|
norm=norm+exp(-((omega_g(i)-omega_g(j))**2)/(2.d0*spectra_broad**2))
|
||
|
|
enddo
|
||
|
|
broad_abs(i)=broad_abs(i)/norm
|
||
|
|
enddo
|
||
|
|
|
||
|
|
!compute DOS using a lorentzian
|
||
|
|
if (ipol==1) then
|
||
|
|
excdos(1:spectra_nstep)=0.d0
|
||
|
|
do i=0,spectra_nstep-1
|
||
|
|
do j=1,n_eig
|
||
|
|
excdos(i+1)=excdos(i+1)+2.d0*eta/(PI*((en(j)-spectra_e_min-dble(i)*step)**2+eta**2))
|
||
|
|
enddo
|
||
|
|
enddo
|
||
|
|
excdos(1:spectra_nstep)=excdos(1:spectra_nstep)/(2.d0*n_eig)
|
||
|
|
endif
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
write(*,*) 'Absorption'
|
||
|
|
write(*,*) 'Energy(eV) Eps2 Eps2(Nogaussbroad)'
|
||
|
|
|
||
|
|
!print absorption spectrum on file
|
||
|
|
if(ionode) then
|
||
|
|
iun = find_free_unit()
|
||
|
|
|
||
|
|
if (ipol==1) then
|
||
|
|
open(unit=iun, file=trim(tmp_dir)//trim(prefix)//'.eps2x.dat', status='unknown', form='formatted')
|
||
|
|
elseif (ipol==2) then
|
||
|
|
open(unit=iun, file=trim(tmp_dir)//trim(prefix)//'.eps2y.dat', status='unknown', form='formatted')
|
||
|
|
elseif (ipol==3) then
|
||
|
|
open(unit=iun, file=trim(tmp_dir)//trim(prefix)//'.eps2z.dat', status='unknown', form='formatted')
|
||
|
|
endif
|
||
|
|
|
||
|
|
do i=1,spectra_nstep
|
||
|
|
write(iun,*) omega_g(i),broad_abs(i), absorption (i)
|
||
|
|
write(*,*) omega_g(i),broad_abs(i), absorption(i)
|
||
|
|
enddo
|
||
|
|
close(iun)
|
||
|
|
endif
|
||
|
|
|
||
|
|
!print excdos spectrum on file
|
||
|
|
if(ionode.and.(ipol==1)) then
|
||
|
|
sumdos=0.d0
|
||
|
|
iun = find_free_unit()
|
||
|
|
open(unit=iun, file=trim(tmp_dir)//trim(prefix)//'.excdos.dat', status='unknown', form='formatted')
|
||
|
|
do i=1,spectra_nstep
|
||
|
|
write(iun,*) omega_g(i),excdos(i)
|
||
|
|
sumdos=sumdos+excdos(i)
|
||
|
|
enddo
|
||
|
|
close(iun)
|
||
|
|
write(*,*) 'sumdos=',sumdos/dble(spectra_nstep)
|
||
|
|
endif
|
||
|
|
|
||
|
|
deallocate(omega_g,absorption,broad_abs,cspectrum,den,campl,excdos)
|
||
|
|
|
||
|
|
call stop_clock('build_spectrum')
|
||
|
|
end subroutine
|
||
|
|
|