Line data Source code
1 : !!****m* ABINIT/m_wfd_optic
2 : !! NAME
3 : !! m_wfd_optic
4 : !!
5 : !! FUNCTION
6 : !! Functions to compute optical matrix elements using the wavefunction descriptor.
7 : !!
8 : !! COPYRIGHT
9 : !! Copyright (C) 2008-2026 ABINIT group (MG)
10 : !! This file is distributed under the terms of the
11 : !! GNU General Public License, see ~abinit/COPYING
12 : !! or http://www.gnu.org/copyleft/gpl.txt .
13 : !!
14 : !! SOURCE
15 :
16 : #if defined HAVE_CONFIG_H
17 : #include "config.h"
18 : #endif
19 :
20 : #include "abi_common.h"
21 :
22 : module m_wfd_optic
23 :
24 : use defs_basis
25 : use m_errors
26 : use m_abicore
27 : use m_xmpi
28 :
29 : use defs_datatypes, only : pseudopotential_type
30 : use m_hide_lapack, only : matrginv
31 : use m_bz_mesh, only : kmesh_t
32 : use m_crystal, only : crystal_t
33 : use m_vkbr, only : vkbr_t, vkbr_free, vkbr_init, nc_ihr_comm
34 : use m_ebands, only : ebands_t
35 : use m_wfd, only : wfdgw_t, wave_t
36 : use m_pawtab, only : pawtab_type
37 : use m_pawcprj, only : pawcprj_type, pawcprj_alloc, pawcprj_free
38 : use m_paw_hr, only : pawhur_t, paw_ihr
39 :
40 : implicit none
41 :
42 : private
43 : !!***
44 :
45 : public :: calc_optical_mels
46 : !!***
47 :
48 : contains
49 : !!***
50 :
51 : !!****f* ABINIT/calc_optical_mels
52 : !! NAME
53 : !! calc_optical_mels
54 : !!
55 : !! FUNCTION
56 : !! Calculate all optical matrix elements in the BZ.
57 : !!
58 : !! INPUTS
59 : !! lomo_spin(Wfd%nsppol)=Index of the lomo band for the different spins.
60 : !! lomo_min,max_band=minimum and max band index to be calculated.
61 : !! nkbz=Number of points in the full Brillouin zone.
62 : !! inclvkb=if different from 0, [Vnl,r] is included in the calculation of the
63 : !! matrix element of the velocity operator. No meaning for PAW (except for DFT+U)
64 : !! qpt(3)
65 : !! Kmesh<kmesh_t>=Info on the k-point sampling for wave functions.
66 : !! Cryst<crystal_t>=Structure defining the crystalline structure.
67 : !! KS_Bst<ebands_t>
68 : !! Pawtab(Cryst%ntypat*usepaw)<pawtab_type>=PAW tabulated starting data
69 : !! Psps <pseudopotential_type>=variables related to pseudopotentials.
70 : !! Hur(Cryst%natom*usepaw)<pawhur_t>=Only for PAW and DFT+U, quantities used to evaluate the commutator [H_u,r].
71 : !! Wfd<wfdgw_t>=Handler for the wavefunctions.
72 : !!
73 : !! OUTPUT
74 : !! opt_cvk(lomo_min:max_band,lomo_min:max_band,nkbz,nsppol)=Matrix elements <c k|e^{+iqr}|v k>
75 : !!
76 : !! SOURCE
77 :
78 180 : subroutine calc_optical_mels(Wfd,Kmesh,KS_Bst,Cryst,Psps,Pawtab,Hur,&
79 180 : & inclvkb,lomo_spin,lomo_min,max_band,nkbz,qpoint,opt_cvk)
80 :
81 : !Arguments ------------------------------------
82 : !scalars
83 : integer,intent(in) :: nkbz,inclvkb,lomo_min,max_band
84 : type(kmesh_t),intent(in) :: Kmesh
85 : type(crystal_t),intent(in) :: Cryst
86 : type(pseudopotential_type),intent(in) :: Psps
87 : type(ebands_t),intent(in) :: KS_Bst
88 : type(wfdgw_t),target,intent(inout) :: Wfd
89 : !arrays
90 : integer,intent(in) :: lomo_spin(Wfd%nsppol)
91 : real(dp),intent(in) :: qpoint(3)
92 : complex(dp),intent(out) :: opt_cvk(lomo_min:max_band,lomo_min:max_band,nkbz,Wfd%nsppol)
93 : type(pawtab_type),intent(in) :: Pawtab(Cryst%ntypat*Wfd%usepaw)
94 : type(pawhur_t),intent(in) :: Hur(Cryst%natom*Wfd%usepaw)
95 :
96 : !Local variables ------------------------------
97 : !scalars
98 : integer :: nsppol,usepaw,nspinor,comm,spin,npw_k,istwf_k,my_nbbp
99 : integer :: ik_bz,ik_ibz,itim_k,isym_k,ib_c,ib_v,ierr,my_rank
100 : real(dp) :: ediff
101 : complex(dp) :: emcvk
102 : character(len=500) :: msg
103 180 : type(vkbr_t) :: vkbr
104 : type(wave_t),pointer :: wave_v, wave_c
105 : !arrays
106 180 : integer,allocatable :: bbp_distrb(:,:)
107 180 : integer,contiguous, pointer :: kg_k(:,:)
108 : real(dp) :: mat_dp(3,3),qrot(3),b1(3),b2(3),b3(3),kbz(3)
109 180 : complex(dp),allocatable :: ir_kibz(:,:,:,:,:)
110 180 : complex(gwp), contiguous, pointer :: ug_c(:),ug_v(:)
111 360 : complex(gwp) :: ihrc(3,Wfd%nspinor**2)
112 360 : logical :: bbp_mask(Wfd%mband,Wfd%mband)
113 180 : type(pawcprj_type),allocatable :: Cp_v(:,:),Cp_c(:,:)
114 : !************************************************************************
115 :
116 180 : call wrtout(std_out," Calculating optical matrix elements in the IBZ","COLL")
117 180 : ABI_CHECK(Wfd%nspinor==1,"nspinor==2 not coded")
118 :
119 180 : comm = Wfd%comm
120 180 : my_rank = Wfd%my_rank
121 :
122 180 : nsppol = Wfd%nsppol
123 180 : nspinor = Wfd%nspinor
124 180 : usepaw = Wfd%usepaw
125 :
126 180 : if (usepaw==1) then
127 84 : ABI_MALLOC(Cp_v,(Wfd%natom,nspinor))
128 12 : call pawcprj_alloc(Cp_v,0,Wfd%nlmn_atm)
129 84 : ABI_MALLOC(Cp_c,(Wfd%natom,nspinor))
130 12 : call pawcprj_alloc(Cp_c,0,Wfd%nlmn_atm)
131 : end if
132 :
133 180 : if (inclvkb==1.and.usepaw==0) then
134 0 : ABI_ERROR("inclvkb==1 not coded,using inclvkb==2")
135 : end if
136 : !
137 : ! Calculate the matrix elements of ir in the IBZ.
138 1080 : ABI_MALLOC(ir_kibz,(3,lomo_min:max_band,lomo_min:max_band,Wfd%nkibz,nsppol))
139 1001316 : ir_kibz=czero
140 :
141 720 : ABI_MALLOC(bbp_distrb, (Wfd%mband,Wfd%mband))
142 :
143 366 : do spin=1,nsppol
144 7122 : do ik_ibz=1,Wfd%nkibz
145 : !
146 : ! Distribute the (b,b') entries.
147 660552 : bbp_mask=.FALSE.; bbp_mask(lomo_spin(spin):max_band,lomo_spin(spin):max_band)=.TRUE.
148 6756 : call wfd%distribute_bbp(ik_ibz,spin,"All",my_nbbp,bbp_distrb,bbp_mask=bbp_mask)
149 72762 : if (ALL(bbp_distrb/=my_rank)) CYCLE
150 :
151 6756 : istwf_k = Wfd%istwfk(ik_ibz)
152 6756 : ABI_CHECK(istwf_k==1,"istwf_k/=1 not coded") ! KB stuff is missing.
153 6756 : npw_k = Wfd%npwarr(ik_ibz)
154 6756 : kg_k => Wfd%Kdata(ik_ibz)%kg_k
155 :
156 6756 : if (inclvkb/=0.and.usepaw==0) then
157 : ! Prepare term i <n,k|[Vnl,r]|n"k>
158 6714 : call vkbr_init(vkbr,Cryst,Psps,inclvkb,istwf_k,npw_k,Kmesh%ibz(:,ik_ibz),kg_k)
159 : end if
160 :
161 : ! Note: spinorial case is not coded therefore we work with ihrc(:,1).
162 : ! TODO: The lower triangle can be Reconstructed by symmetry.
163 46350 : do ib_v=lomo_spin(spin),max_band ! Loop over bands
164 94164 : if ( ALL(bbp_distrb(ib_v,:)/=my_rank) ) CYCLE
165 :
166 39594 : ABI_CHECK(wfd%get_wave_ptr(ib_v, ik_ibz, spin, wave_v, msg) == 0, msg)
167 39594 : ug_v => wave_v%ug
168 39594 : if (usepaw==1) call wfd%get_cprj(ib_v,ik_ibz,spin,Cryst,Cp_v,sorted=.FALSE.)
169 :
170 285000 : do ib_c=lomo_spin(spin),max_band
171 238650 : if (bbp_distrb(ib_v,ib_c)/=my_rank) CYCLE
172 200250 : ABI_CHECK(wfd%get_wave_ptr(ib_c, ik_ibz, spin, wave_c, msg) == 0, msg)
173 200250 : ug_c => wave_c%ug
174 :
175 200250 : if (usepaw==0) then
176 : ! Calculate matrix elements of i[H,r] for NC pseudopotentials.
177 198426 : ihrc = nc_ihr_comm(vkbr,cryst,psps,npw_k,nspinor,istwf_k,inclvkb,Kmesh%ibz(:,ik_ibz),ug_c,ug_v,kg_k)
178 :
179 : else
180 : ! Matrix elements of i[H,r] for PAW.
181 1824 : call wfd%get_cprj(ib_c,ik_ibz,spin,Cryst,Cp_c,sorted=.FALSE.)
182 :
183 1824 : ihrc = paw_ihr(spin,nspinor,npw_k,istwf_k,Kmesh%ibz(:,ik_ibz),Cryst,Pawtab,ug_c,ug_v,kg_k,Cp_c,Cp_v,HUr)
184 : end if
185 : !
186 : ! Save matrix elements of i*r in the IBZ
187 200250 : ediff = KS_Bst%eig(ib_c,ik_ibz,spin) - KS_BSt%eig(ib_v,ik_ibz,spin)
188 200250 : if (ABS(ediff)<tol16) ediff=tol6 ! Treat a possible degeneracy between v and c.
189 840594 : ir_kibz(:,ib_c,ib_v,ik_ibz,spin) = ihrc(:,1)/ediff
190 :
191 : end do !ib_c
192 : end do !ib_v
193 :
194 6942 : call vkbr_free(vkbr)
195 : end do !spin
196 : end do !ik_ibz
197 :
198 : ! Collect results on each node.
199 180 : call xmpi_sum(ir_kibz,comm,ierr)
200 :
201 180 : ABI_FREE(bbp_distrb)
202 :
203 180 : if (usepaw==1) then
204 12 : call pawcprj_free(Cp_v)
205 36 : ABI_FREE(Cp_v)
206 12 : call pawcprj_free(Cp_c)
207 36 : ABI_FREE(Cp_c)
208 : end if
209 : !
210 : ! ======================================================
211 : ! ==== Calculate Fcv(kBZ) in the full Brilouin zone ====
212 : ! ======================================================
213 : !
214 : ! Symmetrization of the matrix elements of the position operator.
215 : ! <Sk b|r|Sk b'> = R <k b|r|k b'> + \tau \delta_{bb'}
216 : ! where S is one of the symrec operations in reciprocal space, R is the
217 : ! corresponding operation in real space, \tau being the associated fractional translations.
218 : !
219 : ! q.Mcv( Sk) = S^{-1}q. Mcv(k)
220 : ! q.Mcv(-Sk) = -S^{-1}q. CONJG(Mcv(k)) if time-reversal is used.
221 :
222 720 : b1=Cryst%gprimd(:,1)*two_pi
223 720 : b2=Cryst%gprimd(:,2)*two_pi
224 720 : b3=Cryst%gprimd(:,3)*two_pi
225 :
226 384126 : opt_cvk = czero
227 366 : do spin=1,nsppol
228 8862 : do ik_bz=1,nkbz
229 : !
230 : ! Get ik_ibz, and symmetries index from ik_bz.
231 8496 : call Kmesh%get_BZ_item(ik_bz,kbz,ik_ibz,isym_k,itim_k)
232 :
233 110448 : mat_dp = DBLE(Cryst%symrec(:,:,isym_k))
234 8496 : call matrginv(mat_dp,3,3) ! Invert
235 135936 : qrot = (3-2*itim_k) * MATMUL(mat_dp,qpoint)
236 :
237 60426 : do ib_v=lomo_spin(spin),max_band ! Loops over the bands C and V start
238 383760 : do ib_c=lomo_spin(spin),max_band
239 : !if (ib_c==ib_v) CYCLE
240 323520 : emcvk = pdtqrc(qrot,ir_kibz(:,ib_c,ib_v,ik_ibz,spin),b1,b2,b3)
241 323520 : if (itim_k==2) emcvk = CONJG(emcvk)
242 375264 : opt_cvk(ib_c,ib_v,ik_bz,spin) = emcvk
243 : end do !ib_c
244 : end do !ib_v
245 :
246 : end do !ik_bz
247 : end do !spin
248 :
249 180 : ABI_FREE(ir_kibz)
250 :
251 540 : call xmpi_barrier(comm)
252 :
253 : contains
254 : !!***
255 :
256 : !!****f* ABINIT/pdtqrc
257 : !! NAME
258 : !! pdtqrc
259 : !!
260 : !! FUNCTION
261 : !! Calculate the dot product of a real vector with a complex vector, where each is in terms of b1-b3
262 : !!
263 : !! INPUTS
264 : !!
265 : !! OUTPUT
266 : !!
267 : !! SOURCE
268 :
269 323520 : pure function pdtqrc(R,C,b1,b2,b3)
270 :
271 : !Arguments ------------------------------------
272 : !arrays
273 : real(dp),intent(in) :: R(3),b1(3),b2(3),b3(3)
274 : complex(dp),intent(in) :: C(3)
275 : complex(dp) :: pdtqrc
276 :
277 : !Local variables ------------------------------
278 : !scalars
279 : integer :: ii
280 : !************************************************************************
281 :
282 323520 : pdtqrc=czero
283 1294080 : do ii=1,3
284 : pdtqrc = pdtqrc + (R(1)*b1(ii)+R(2)*b2(ii)+R(3)*b3(ii)) * &
285 1294080 : & (C(1)*b1(ii)+C(2)*b2(ii)+C(3)*b3(ii))
286 : end do
287 :
288 323520 : end function pdtqrc
289 : !!***
290 :
291 : end subroutine calc_optical_mels
292 : !!***
293 :
294 : end module m_wfd_optic
295 : !!***
|
