scf Module Reference

Functions/Subroutines
subroutine	scf_loop ()
subroutine	kohn_sham_eq (linit, Fvec)
subroutine	initialize_wf (psi)
	Initialize wave function with random number. More...

Variables
integer, save	electron_maxstep
	Max number of iteration. More...
real(8), save	mixing_beta
	Mixing for SCF. More...
real(8), save	conv_thr
	Convergence threshold [Htr]. More...

Function/Subroutine Documentation

scf_loop()

subroutine scf::scf_loop

Definition at line 36 of file scf.F90.

    !
    use gvec, only : g_rh
    use rho_v, only : vks
    use constant, only : htr2ev
    !
    integer :: istep, jstep
    logical :: linit
    real(8) :: alpha, res, &
    &          Fvec0(g_rh%nr), dVks(g_rh%nr), Fvec(g_rh%nr), dFvec(g_rh%nr), &
    &          jacob1(g_rh%nr,2:electron_maxstep), jacob2(g_rh%nr,2:electron_maxstep)
    !
    linit = .true.
    !
    do istep = 1, electron_maxstep
       !
       write(*,*) "  Iteration ", istep
       !
       call kohn_sham_eq(linit, fvec)
       linit = .false.
       res = sqrt(dot_product(fvec(1:g_rh%nr), fvec(1:g_rh%nr))) / dble(g_rh%nr)
       write(*,*) "    delta Vks [eV] : ", res * htr2ev
       if(res < conv_thr) exit
       !
       if(istep > 1) then
          !
          ! Update Jacobian with dFvec
          !
          dfvec(1:g_rh%nr) = fvec(1:g_rh%nr) - fvec0(1:g_rh%nr)
          !
          jacob1(1:g_rh%nr,istep) = mixing_beta * dfvec(1:g_rh%nr) + dvks(1:g_rh%nr)
          do jstep = 2, istep - 1
             alpha = dot_product(jacob2(1:g_rh%nr,jstep), dfvec(1:g_rh%nr))
             jacob1(1:g_rh%nr,istep) = jacob1(1:g_rh%nr,istep) - jacob1(1:g_rh%nr,jstep) * alpha
          end do
          !
          alpha = dot_product(dfvec(1:g_rh%nr), dfvec(1:g_rh%nr))
          jacob2(1:g_rh%nr,istep) = dfvec(1:g_rh%nr) / alpha
          !
       end if
       !
       ! Compute dVks with new Jacobian & Fvec
       !
       dvks(1:g_rh%nr) = mixing_beta * fvec(1:g_rh%nr)
       do jstep = 2, istep
          alpha = dot_product(jacob2(1:g_rh%nr,jstep), fvec(1:g_rh%nr))
          dvks(1:g_rh%nr) = dvks(1:g_rh%nr) - jacob1(1:g_rh%nr,jstep) * alpha 
       end do
       fvec0(1:g_rh%nr) = fvec(1:g_rh%nr)
       !
       vks(1:g_rh%nr) = vks(1:g_rh%nr) + dvks(1:g_rh%nr)
       !
    end do ! istep
    !
    if(istep >= electron_maxstep) then
       write(*,'(/,7x,"Not converged ! res = ",e12.5,/)') res
    else
       write(*,'(/,7x,"Converged ! iter = ",i0,/)') istep
    end if
    !

References conv_thr, electron_maxstep, gvec::g_rh, constant::htr2ev, kohn_sham_eq(), mixing_beta, and rho_v::vks.

Referenced by pwdft().

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kohn_sham_eq()

subroutine scf::kohn_sham_eq	(	logical, intent(in)	linit,
		real(8), dimension(g_rh%nr), intent(out)	Fvec
	)

Definition at line 100 of file scf.F90.

    !
    use gvec, only : g_wf, g_rh
    use kohn_sham, only : nbnd, eval, evec, calculation
    use k_point, only : kvec, nk, ksum_rho
    use rho_v, only : vks, vps, hartree_pot, xc_pot
    use diag_direct, only : direct
    use lobpcg, only : lobpcg_main
    !
    logical,intent(in) :: linit
    real(8),intent(out) :: Fvec(g_rh%nr)
    !
    integer :: ik, istep, avestep
    !
    if(calculation == "direct") then
       do ik = 1, nk
          call direct(g_wf%npw,kvec(1:3,ik),evec(1:g_wf%npw,1:nbnd,ik),eval(1:nbnd,ik))
       end do
    else
       avestep = 0
       if(linit) call initialize_wf(evec(1:g_wf%npw,1:nbnd,1))
       do ik = 1, nk
          call lobpcg_main(g_wf%npw, kvec(1:3,ik),&
          &                evec(1:g_wf%npw,1:nbnd,ik),eval(1:nbnd,ik), istep)
          avestep = avestep + istep
          if(linit .and. ik /= nk) evec(1:g_wf%npw,1:nbnd,ik+1) &
          &                      = evec(1:g_wf%npw,1:nbnd,ik)
       end do
       write(*,*) "    Average LOBPCG steps : ", avestep / nk
    end if
    !
    if(calculation == "scf") then
       !
       call ksum_rho()
       !
       fvec(1:g_rh%nr) = vps(1:g_rh%nr)
       call hartree_pot(fvec)
       call xc_pot(fvec)
       !
       fvec(1:g_rh%nr) = fvec(1:g_rh%nr) - vks(1:g_rh%nr)
       !
    else
       fvec(1:g_rh%nr) = 0.0d0
    end if
    !

References kohn_sham::calculation, diag_direct::direct(), kohn_sham::eval, kohn_sham::evec, gvec::g_rh, gvec::g_wf, rho_v::hartree_pot(), initialize_wf(), k_point::ksum_rho(), k_point::kvec, lobpcg::lobpcg_main(), kohn_sham::nbnd, k_point::nk, rho_v::vks, rho_v::vps, and rho_v::xc_pot().

Referenced by pwdft(), and scf_loop().

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initialize_wf()

subroutine scf::initialize_wf

(

complex(8), dimension(g_wf%npw,nbnd), intent(out)

psi

)

Initialize wave function with random number.

Definition at line 149 of file scf.F90.

    !
    use kohn_sham, only : nbnd
    use gvec, only : g_wf
    !
    complex(8),intent(out) :: psi(g_wf%npw,nbnd)
    !
    integer :: ibnd, nseed
    integer :: seed(256)
    real(8) :: rpsi(g_wf%npw,nbnd), ipsi(g_wf%npw,nbnd), norm
    !
    call random_seed(size=nseed)
    seed(1:nseed)=2
    call random_seed(put=seed)
    call random_number(rpsi)
    call random_number(ipsi)
    !
    psi(1:g_wf%npw,1:nbnd) = cmplx(rpsi(1:g_wf%npw,1:nbnd), &
    &                              ipsi(1:g_wf%npw,1:nbnd), 8)
    !
    do ibnd = 1, nbnd
       norm = sqrt(dble(dot_product(psi(1:g_wf%npw,ibnd), psi(1:g_wf%npw,ibnd))))
       psi(1:g_wf%npw,ibnd) = psi(1:g_wf%npw,ibnd) / norm
    end do
    !

References gvec::g_wf, and kohn_sham::nbnd.

Referenced by kohn_sham_eq().

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Variable Documentation

electron_maxstep

integer, save scf::electron_maxstep

Max number of iteration.

Definition at line 27 of file scf.F90.

  integer,save :: &
  & electron_maxstep !< Max number of iteration

Referenced by stdin::read_stdin(), and scf_loop().

mixing_beta

real(8), save scf::mixing_beta

Mixing for SCF.

Definition at line 29 of file scf.F90.

  real(8),save :: &
  & mixing_beta, & !< Mixing for SCF
  & conv_thr !< Convergence threshold [Htr]

Referenced by stdin::read_stdin(), and scf_loop().

conv_thr

real(8), save scf::conv_thr

Convergence threshold [Htr].

Definition at line 29 of file scf.F90.

Referenced by stdin::read_stdin(), and scf_loop().