! ! Copyright (C) 2001-2009 Quantum ESPRESSO group ! This file is distributed under the terms of the ! GNU General Public License. See the file `License' ! in the root directory of the present distribution, ! or http://www.gnu.org/copyleft/gpl.txt . ! !------------------------------------------------------------------------------- SUBROUTINE solve_direct_shift(dvbarein, iw, drhoscf) !----------------------------------------------------------------------------- ! HL ! Driver routine for the solution of the linear system which ! defines the change of the wavefunction due to a perturbing potential ! parameterized in r and iw. i.e. v_{r, iw} (r') ! It performs the following tasks: ! a) computes the bare potential term Delta V | psi > ! b) adds to it the screening term Delta V_{SCF} | psi > ! c) applies P_c^+ (orthogonalization to valence states) ! d) calls c_bi_cgsolve_all to solve the linear system ! e) computes Delta rho, Delta V_{SCF}. ! Currently symmetrized in terms of mode etc. Might need to strip this out ! and check PW for how it stores/symmetrizes charge densities. !---------------------------------------------------------------------------- !------------------------------------------------------------------------------ USE kinds, ONLY : DP USE ions_base, ONLY : nat, ntyp => nsp, ityp USE io_global, ONLY : stdout, ionode USE io_files, ONLY : prefix, iunigk USE check_stop, ONLY : check_stop_now USE wavefunctions_module, ONLY : evc USE constants, ONLY : degspin USE cell_base, ONLY : tpiba2 USE ener, ONLY : ef USE klist, ONLY : lgauss, degauss, ngauss, xk, wk, nkstot USE gvect, ONLY : nrxx, g, nl, nr1, nr2, nr3, nrx1, nrx2, nrx3 USE gsmooth, ONLY : doublegrid, nrxxs, nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s USE lsda_mod, ONLY : lsda, nspin, current_spin, isk USE spin_orb, ONLY : domag USE wvfct, ONLY : nbnd, npw, npwx, igk,g2kin, et USE scf, ONLY : rho USE uspp, ONLY : okvan, vkb USE uspp_param, ONLY : upf, nhm, nh USE noncollin_module, ONLY : noncolin, npol, nspin_mag USE paw_variables, ONLY : okpaw USE paw_onecenter, ONLY : paw_dpotential, paw_dusymmetrize, & paw_dumqsymmetrize USE control_gw, ONLY : rec_code, niter_gw, nmix_gw, tr2_gw, & alpha_pv, lgamma, lgamma_gamma, convt, & nbnd_occ, alpha_mix, ldisp, rec_code_read, & where_rec, flmixdpot, current_iq, & ext_recover, eta USE nlcc_gw, ONLY : nlcc_any USE units_gw, ONLY : iudrho, lrdrho, iudwf, lrdwf, iubar, lrbar, & iuwfc, lrwfc, iunrec, iudvscf, iudwfm, iudwfp USE output, ONLY : fildrho, fildvscf USE gwus, ONLY : int3_paw, becsumort USE eqv, ONLY : dvpsi, dpsi, evq, eprec, dpsim, dpsip USE qpoint, ONLY : xq, npwq, igkq, nksq, ikks, ikqs USE modes, ONLY : npertx, npert, u, t, irotmq, tmq, & minus_q, irgq, nsymq, rtau USE recover_mod, ONLY : read_rec, write_rec ! used oly to write the restart file USE mp_global, ONLY : inter_pool_comm, intra_pool_comm, mpime, mp_global_end,& intra_image_comm USE mp, ONLY : mp_sum, mp_barrier ! USE freq_gw, ONLY : fpol, fiu, nfs, nfsmax implicit none ! counter on frequencies. integer :: iw integer :: irr, imode0, npe ! input: the irreducible representation ! input: the number of perturbation ! input: the position of the modes complex(DP) :: drhoscf (nrxx, nspin_mag, nfs) ! output: the change of the scf charge complex(DP) :: dvbarein (nrxxs) complex(DP), allocatable :: dpsiwp(:,:), dpsiwm(:,:) ! HL prec ! HL careful now... complexifying preconditioner: real(DP) , allocatable :: h_diag (:,:) ! h_diag: diagonal part of the Hamiltonian real(DP) :: thresh, anorm, averlt, dr2 real(DP) :: x !keeps track of iterations for seed system INTEGER, ALLOCATABLE :: niters(:) INTEGER :: gveccount , ngvecs ! thresh: convergence threshold ! anorm : the norm of the error ! averlt: average number of iterations ! dr2 : self-consistency error real(DP) :: dos_ef, weight, aux_avg (2) ! Misc variables for metals ! dos_ef: density of states at Ef real(DP), external :: w0gauss, wgauss ! functions computing the delta and theta function complex(DP), allocatable, target :: dvscfin(:,:) ! change of the scf potential complex(DP), pointer :: dvscfins (:,:) ! change of the scf potential (smooth part only) complex(DP), allocatable :: drhoscfh (:,:,:), dvscfout (:,:,:) ! change of rho / scf potential (output) ! change of scf potential (output) complex(DP), allocatable :: ldos (:,:), ldoss (:,:), mixin(:), mixout(:), & dbecsum (:,:,:), dbecsum_nc(:,:,:,:,:), aux1 (:,:) complex(DP) :: cw complex(DP), allocatable :: etc(:,:) !HL dbecsum (:,:,:,:), dbecsum_nc(:,:,:,:,:), aux1 (:,:) ! Misc work space ! ldos : local density of states af Ef ! ldoss: as above, without augmentation charges ! dbecsum: the derivative of becsum ! becsum1 PAW array. REAL(DP), allocatable :: becsum1(:,:,:) COMPLEX (DP), ALLOCATABLE :: hpsi(:,:) !For approx, mixing scheme. real(kind=DP) :: DZNRM2 complex(kind=DP) :: ZDOTC external ZDOTC, DZNRM2 logical :: conv_root, & ! true if linear system is converged exst, & ! used to open the recover file lmetq0, & ! true if xq=(0,0,0) in a metal cgsolver integer :: kter, & ! counter on iterations iter0, & ! starting iteration ipert, & ! counter on perturbations ibnd, & ! counter on bands iter, & ! counter on iterations lter, & ! counter on iterations of linear system ltaver, & ! average counter lintercall, & ! average number of calls to cgsolve_all ik, ikk, & ! counter on k points ikq, & ! counter on k+q points ig, & ! counter on G vectors ndim, & ! integer actual row dimension of dpsi is, & ! counter on spin polarizations nt, & ! counter on types na, & ! counter on atoms nrec, nrec1,& ! the record number for dvpsi and dpsi ios, & ! integer variable for I/O control mode, & ! mode index igpert, & ! bare perturbation g vector. lmres ! number of gmres iterations to include when using bicgstabl. real(DP) :: tcpu, get_clock ! timing variables real(DP) :: meandvb !external ch_psi_all, cg_psi, ccg_psi, cch_psi_all_fix external ch_psi_all, cg_psi, cch_psi_all_fix IF (rec_code_read > 20 ) RETURN !HL- Allocate arrays for dV_scf (need to alter these from (nrxx, nspin_mag, npe) to just (nrxx, nspin_mag). npe = 1 imode0 = 1 irr = 1 ipert = 1 lter = 0 lmres = 1 call start_clock ('solve_linter') allocate (dvscfout ( nrxx , nspin_mag, nfs)) allocate (dvscfin ( nrxx , nspin_mag)) allocate (dpsiwm (npwx, nfs)) allocate (dpsiwp (npwx, nfs)) if (doublegrid) then allocate (dvscfins ( nrxxs , nspin_mag)) else dvscfins => dvscfin endif allocate (drhoscfh ( nrxx, nspin_mag, nfs)) allocate (dbecsum ( (nhm * (nhm + 1))/2 , nat, nspin_mag)) !Complex eigenvalues allocate (etc(nbnd, nkstot)) IF (okpaw) THEN allocate (mixin(nrxx*nspin_mag+(nhm*(nhm+1)*nat*nspin_mag)/2) ) allocate (mixout(nrxx*nspin_mag+(nhm*(nhm+1)*nat*nspin_mag)/2) ) mixin=(0.0_DP,0.0_DP) ENDIF IF (noncolin) allocate (dbecsum_nc (nhm,nhm, nat , nspin, npe)) allocate (aux1 ( nrxxs, npol)) allocate (h_diag ( npwx*npol, nbnd)) iter0 = 0 convt =.FALSE. where_rec='no_recover' IF (convt) GOTO 155 IF (iter0==-1000) iter0=0 ! No self-consistency: do kter = 1, 1 iter = kter + iter0 ltaver = 0 lintercall = 0 drhoscf(:,:,:) = (0.d0, 0.d0) dbecsum(:,:,:) = (0.d0, 0.d0) IF (noncolin) dbecsum_nc = (0.d0, 0.d0) if (nksq.gt.1) rewind (unit = iunigk) !start kpoints loop do ik = 1, nksq if (nksq.gt.1) then read (iunigk, err = 100, iostat = ios) npw, igk 100 call errore ('solve_linter', 'reading igk', abs (ios) ) endif ! lgamma is a q=0 computation if (lgamma) npwq = npw ! k and k+q mesh defined in initialize_gw: ! ikks(ik) = 2 * ik - 1 ! ikqs(ik) = 2 * ik ikk = ikks(ik) ikq = ikqs(ik) if (lsda) current_spin = isk (ikk) if (.not.lgamma.and.nksq.gt.1) then read (iunigk, err = 200, iostat = ios) npwq, igkq 200 call errore ('solve_linter', 'reading igkq', abs (ios) ) endif !Calculates beta functions (Kleinman-Bylander projectors), with !structure factor, for all atoms, in reciprocal space !HL the beta functions (vkb) are being generated properly. call init_us_2 (npwq, igkq, xk (1, ikq), vkb) !Reads unperturbed wavefuctions psi(k) and psi(k+q) if (nksq.gt.1) then if (lgamma) then call davcio (evc, lrwfc, iuwfc, ikk, - 1) else call davcio (evc, lrwfc, iuwfc, ikk, - 1) call davcio (evq, lrwfc, iuwfc, ikq, - 1) endif endif do ig = 1, npwq g2kin (ig) = ( (xk (1,ikq) + g (1, igkq(ig)) ) **2 + & (xk (2,ikq) + g (2, igkq(ig)) ) **2 + & (xk (3,ikq) + g (3, igkq(ig)) ) **2 ) * tpiba2 enddo !No preconditioning in multishift. h_diag = 0.d0 do ibnd = 1, nbnd_occ (ikk) do ig = 1, npwq h_diag(ig,ibnd) = 1.0d0 enddo enddo !HL indices freezing perturbations. mode = 1 nrec = ik !and now adds the contribution of the self consistent term if (where_rec =='solve_lint'.or.iter>1) then !After the first iteration dvbare_q*psi_kpoint is read from file call davcio (dvpsi, lrbar, iubar, nrec, - 1) !calculates dvscf_q*psi_k in G_space, for all bands, k=kpoint !dvscf_q from previous iteration (mix_potential) call start_clock ('vpsifft') do ibnd = 1, nbnd_occ (ikk) !FFT translated according to igk call cft_wave (evc (1, ibnd), aux1, +1) call apply_dpot(aux1, dvscfins(1,1), current_spin) !FFT translated according to igkq: DeltaV(q)psi(k). call cft_wave (dvpsi (1, ibnd), aux1, -1) enddo call stop_clock ('vpsifft') else ! At the first iteration dvbare_q*psi_kpoint is calculated ! and written to file call dvqpsi_us (dvbarein, ik, 1, .false.) ! call davcio (dvpsi, lrbar, iubar, nrec, +1) endif ! Orthogonalize dvpsi to valence states: ps = ! Apply -P_c^+. ! -P_c^ = - (1-P_v^): CALL orthogonalize(dvpsi, evq, ikk, ikq, dpsi) ! ! At the first iteration dpsi and dvscfin are set to zero ! dpsi(:,:) = (0.d0, 0.d0) dpsim(:,:) = (0.d0, 0.d0) dpsip(:,:) = (0.d0, 0.d0) dvscfin(:, :) = (0.d0, 0.d0) ! starting threshold for iterative solution of the linear system thresh = tr2_gw etc(:,:) = CMPLX(et(:,:), 0.0d0 , kind=DP) !want to construct full frequency density response, one band at a time, !for each k. gveccount = 1 ngvecs = 1 if(.not.allocated(niters)) ALLOCATE(niters(ngvecs)) niters = 0 do ibnd = 1, nbnd_occ(ikk) call cbcg_solve_coul(cch_psi_all_fix, cg_psi, etc(1,ikk), dvpsi(:,ibnd), dpsip, h_diag, & npwx, npwq, thresh, ik, lter, conv_root, anorm, 1, npol, & cw, niters(gveccount)) if (.not.conv_root) WRITE(1000+mpime, '(5x,"kpoint",i4," ibnd",i4, & & "solve_linter: root not converged ",e10.3)') & & ik , ibnd, anorm call coul_multishift(npwx, npwq, nfs, niters(gveccount), -fiu(iw), 1, dpsiwm(:,:)) call coul_multishift(npwx, npwq, nfs, niters(gveccount), fiu(iw), 1, dpsiwp(:,:)) ltaver = ltaver + lter lintercall = lintercall + 1 nrec1 = ik dpsi(:,:) = (0.5d0,0.0d0) * (dpsiwm(:,:) + dpsiwp(:,:)) !calculates dvscf, sum over k => dvscf_q_ipert !incdrhoscf: This routine computes the change of the charge !density due to the perturbation. It is called at the end of !the computation of the change of the wavefunction for a given !k point. weight = wk (ikk) do iw = 1, nfs call incdrhoscf(drhoscf(1, current_spin, iw), weight, ik, & dbecsum(1,1,current_spin)) enddo!iw enddo !ibnd enddo if (doublegrid) then do is = 1, nspin_mag call cinterpolate (drhoscfh(1,is,1), drhoscf(1,is,1), 1) enddo else call zcopy (nspin_mag*nrxx, drhoscf, 1, drhoscfh, 1) endif !No USPP: ! call addusddens (drhoscfh, dbecsum, imode0, npe, 0) call zcopy (nrxx*nspin_mag, drhoscfh(1,1,1), 1, dvscfout(1,1,1), 1) ! SGW: here we enforce zero average variation of the charge density ! if the bare perturbation does not have a constant term ! (otherwise the numerical error, coupled with a small denominator ! in the coulomb term, gives rise to a spurious dvscf response) ! One wing of the dielectric matrix is particularly badly behaved meandvb = sqrt ( (sum(dreal(dvbarein)))**2.d0 + (sum(aimag(dvbarein)))**2.d0 ) / float(nrxxs) do iw = 1, nfs if (meandvb.lt.1.d-8) then call cft3 (dvscfout(1,1,iw), nr1, nr2, nr3, nrx1, nrx2, nrx3, -1) dvscfout ( nl(1), current_spin, iw) = dcmplx(0.d0, 0.0d0) call cft3 (dvscfout(1,1,iw), nr1, nr2, nr3, nrx1, nrx2, nrx3, 1) endif enddo do iw = 1, nfs call dv_of_drho (1, dvscfout(1,1,iw), .true.) enddo if (doublegrid) then do ipert = 1, npe do is = 1, nspin_mag call cinterpolate (dvscfin(1,is), dvscfins(1,is), -1) enddo enddo endif ! with the new change of the potential we compute the integrals ! of the change of potential and Q ! HL-Q denotes the augmentation charge. Look at Vanderbilt PRB 41 7892 ! Q_{ij} = - ! USPP valence charge density is described ! n_v(r) = \sum_{n,k} \phi^{*}_{nk} (r) \phi_{nk}(r) + \sum_{i,j} p_{i,j}Q_{j,i} ! p_{i,j} = \sum_{n,k} #ifdef __PARA aux_avg (1) = DBLE (ltaver) aux_avg (2) = DBLE (lintercall) averlt = aux_avg (1) / aux_avg (2) #else averlt = DBLE (ltaver) / lintercall #endif tcpu = get_clock ('GW') dr2 = dr2 / DBLE(npe) CALL flush_unit( stdout ) rec_code=10 enddo !loop on kter (iterations) 155 iter0=0 ! -vc*\Chi do iw = 1 , nfs drhoscf(:,1,iw) = -dvscfout(:,1,iw) enddo if (convt) then if (fildvscf.ne.' ') then write(6, '("fildvscf")') end if endif deallocate (h_diag) deallocate (aux1) deallocate (dbecsum) IF (okpaw) THEN if (lmetq0.and.allocated(becsum1)) deallocate (becsum1) deallocate (mixin) deallocate (mixout) ENDIF IF (noncolin) deallocate (dbecsum_nc) deallocate (dvscfout) deallocate (drhoscfh) if (doublegrid) deallocate (dvscfins) deallocate (dvscfin) call stop_clock ('solve_linter') END SUBROUTINE solve_direct_shift