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1 : !!****m* ABINIT/m_xcdata
2 : !! NAME
3 : !! m_xcdata
4 : !!
5 : !! FUNCTION
6 : !! This module provides the definition of
7 : !! the xcdata_type used to drive the computation of the XC energy, potential, kernel, etc.
8 : !!
9 : !! COPYRIGHT
10 : !! Copyright (C) 2017-2026 ABINIT group (XG)
11 : !! This file is distributed under the terms of the
12 : !! GNU General Public License, see ~abinit/COPYING
13 : !! or http://www.gnu.org/copyleft/gpl.txt .
14 : !!
15 : !! NOTES
16 : !!
17 : !! SOURCE
18 :
19 : #if defined HAVE_CONFIG_H
20 : #include "config.h"
21 : #endif
22 :
23 : #include "abi_common.h"
24 :
25 : module m_xcdata
26 :
27 : use defs_basis
28 : use m_errors
29 : use libxc_functionals
30 : use m_dtset, only : dataset_type
31 : use m_drivexc, only : size_dvxc
32 :
33 : implicit none
34 :
35 : private
36 :
37 : !!***
38 :
39 : !!****t* m_xcdata/xcdata_type
40 : !! NAME
41 : !! xcdata_type
42 : !!
43 : !! FUNCTION
44 : !! This object stores the input variables (and derived parameters) needed to compute the exchange-correlation functional,
45 : !! not simply to define it.
46 : !!
47 : !! NOTES
48 : !!
49 : !! SOURCE
50 :
51 : type, public :: xcdata_type
52 :
53 : ! Integer scalars
54 :
55 : integer :: auxc_ixc
56 : ! Choice of auxiliary exchange-correlation functional. See input variable documentation
57 : ! If 0, there is no auxiliary xc functional, the one corresponding to ixc has to be used.
58 :
59 : integer :: intxc
60 : ! 1 if the XC functional has to be interpolated on a more refined mesh than the FFT one.
61 : ! 0 stick to the original FFT mesh
62 :
63 : integer :: ixc
64 : ! Choice of exchange-correlation functional. See input variable documentation
65 :
66 : integer :: nspden
67 : ! Number of spin components of the density
68 :
69 : integer :: usefock
70 : ! 1 if the XC functional includes a (possibly screened) Fock contribution
71 :
72 : integer :: usegradient
73 : ! 1 if the XC functional depends on the density gradient
74 :
75 : integer :: uselaplacian
76 : ! 1 if the XC functional depends on the density laplacian
77 :
78 : integer :: usekden
79 : ! 1 if the XC functional depends on the kinetic energy density
80 :
81 : integer :: vdw_xc
82 : ! Choice of van-der-Waals density functional. See input variable documentation
83 :
84 : integer :: xclevel
85 : ! Determined from ixc
86 : ! 0 if no XC functional
87 : ! 1 if LDA-type XC functional
88 : ! 2 if GGA-type XC functional
89 : ! 3 if for TDDFT kernel
90 :
91 : ! Real scalars
92 :
93 : real(dp) :: hyb_mixing
94 : ! Parameter for mixing Fock exchange in native PBEx functionals
95 :
96 : real(dp) :: nelect
97 : ! Number of electrons in the cell (for Fermi-Amaldi only)
98 :
99 : real(dp) :: tphysel
100 : ! Physical temperature (for temperature-dependent functional)
101 :
102 : real(dp) :: xc_denpos
103 : ! density positivity value
104 :
105 : real(dp) :: xc_taupos
106 : ! kinetic energy density positivity value (mGGA)
107 :
108 : end type xcdata_type
109 :
110 : !----------------------------------------------------------------------
111 :
112 : public :: xcdata_init ! Initialize the object.
113 : public :: get_xclevel ! Get the xclevel from ixc (as well as usefock)
114 : public :: get_auxc_ixc ! Get the auxiliary xc functional (if it exists)
115 :
116 : contains
117 : !!***
118 :
119 : !!****f* m_xcdata/xcdata_init
120 : !! NAME
121 : !! xcdata_init
122 : !!
123 : !! FUNCTION
124 : !! Init the structure. Mostly copy input variables, except compute and usefock and xclevel.
125 : !!
126 : !! INPUTS
127 : !! [dtset = the dataset from which the other input variables are taken, if they are not present]
128 : !! [auxc_ixc = possibly the index of the auxiliary xc functional, otherwise 0.]
129 : !! [hyb_mixing = parameter for mixing Fock exchange in native PBEx functionals]
130 : !! [intxc = 1 if the XC functional has to be interpolated on a more refined mesh than the FFT one]
131 : !! [ixc= index of exchange-correlation functional]
132 : !! [nelect = Number of electrons in the cell (for Fermi-Amaldi only)]
133 : !! [tphysel = Physical temperature (for temperature-dependent functional)]
134 : !! [vdw_xc = Choice of van-der-Waals density functional]
135 : !! [xc_denpos = density positivity value]
136 : !! [xc_taupos = kinetic energy density positivity value (mGGA)]
137 : !!
138 : !! OUTPUT
139 : !! xcdata <type(xcdata_type)>= the data to calculate exchange-correlation are initialized
140 : !!
141 : !! SOURCE
142 :
143 56611 : subroutine xcdata_init(xcdata,auxc_ixc,dtset,hyb_mixing,intxc,ixc,nelect,nspden,tphysel,&
144 : & vdw_xc,xc_denpos,xc_taupos)
145 :
146 : !Arguments ------------------------------------
147 : !scalars
148 : integer, intent(in),optional :: auxc_ixc,intxc,ixc,nspden,vdw_xc
149 : real(dp),intent(in),optional :: hyb_mixing,nelect,tphysel,xc_denpos,xc_taupos
150 : type(dataset_type), intent(in),optional :: dtset
151 : type(xcdata_type), intent(out) :: xcdata
152 : !Local variables-------------------------------
153 : integer :: nspden_updn
154 : character(len=500) :: msg
155 :
156 : ! *************************************************************************
157 :
158 56611 : if(present(dtset))then
159 56611 : xcdata%auxc_ixc=dtset%auxc_ixc
160 56611 : xcdata%intxc=dtset%intxc
161 56611 : xcdata%ixc=dtset%ixc
162 56611 : xcdata%nspden=dtset%nspden
163 56611 : xcdata%vdw_xc=dtset%vdw_xc
164 :
165 56611 : xcdata%hyb_mixing=abs(dtset%hyb_mixing) ! Warning : the absolute value is needed, because of the singular way
166 : ! to define the default values for this input variable.
167 56611 : xcdata%nelect=dtset%nelect
168 56611 : xcdata%tphysel=merge(dtset%tphysel,dtset%tsmear,dtset%tphysel>tol8.and.dtset%occopt/=3.and.dtset%occopt/=9)
169 :
170 56611 : xcdata%xc_denpos=dtset%xc_denpos
171 56611 : xcdata%xc_taupos=dtset%xc_taupos
172 :
173 : else
174 0 : if(.not.(present(auxc_ixc).and.present(intxc).and.present(ixc).and.&
175 : & present(vdw_xc).and.present(hyb_mixing).and.&
176 : & present(nelect).and.present(nspden).and.&
177 : & present(tphysel).and.present(xc_denpos).and.present(xc_taupos)))then
178 0 : msg='If dtset is not provided, all the other optional arguments must be provided, which is not the case!'
179 0 : ABI_BUG(msg)
180 : endif
181 : endif
182 :
183 56611 : if(present(auxc_ixc)) xcdata%auxc_ixc=auxc_ixc
184 56611 : if(present(intxc)) xcdata%intxc=intxc
185 56611 : if(present(ixc)) xcdata%ixc=ixc
186 56611 : if(present(nspden)) xcdata%nspden=nspden
187 56611 : if(present(vdw_xc)) xcdata%vdw_xc=vdw_xc
188 :
189 56611 : if(present(hyb_mixing))xcdata%hyb_mixing=hyb_mixing
190 56611 : if(present(nelect)) xcdata%nelect=nelect
191 56611 : if(present(tphysel)) xcdata%tphysel=tphysel
192 56611 : if(present(xc_denpos)) xcdata%xc_denpos=xc_denpos
193 56611 : if(present(xc_taupos)) xcdata%xc_taupos=xc_taupos
194 :
195 : !Compute xclevel
196 56611 : call get_xclevel(xcdata%ixc,xcdata%xclevel,usefock=xcdata%usefock)
197 :
198 : !Compute usegradient,uselaplacian,usekden
199 56611 : nspden_updn=min(xcdata%nspden,2)
200 : call size_dvxc(xcdata%ixc,1,nspden_updn,usegradient=xcdata%usegradient,&
201 56611 : & uselaplacian=xcdata%uselaplacian,usekden=xcdata%usekden)
202 :
203 56611 : end subroutine xcdata_init
204 : !!***
205 :
206 : !----------------------------------------------------------------------
207 :
208 : !!****f* m_xcdata/get_xclevel
209 : !! NAME
210 : !! get_xclevel
211 : !!
212 : !! FUNCTION
213 : !! Compute xclevel.
214 : !!
215 : !! INPUTS
216 : !! ixc= index of exchange-correlation functional
217 : !!
218 : !! OUTPUT
219 : !! [usefock = 1 if the XC functional needs the Fock operator]
220 : !! xclevel= 0 if no XC functional except possibly Fock; 1 if LDA; 2 if GGA ; 3 for TDDFT kernel tests
221 : !!
222 : !! SOURCE
223 :
224 63793 : subroutine get_xclevel(ixc, xclevel, usefock)
225 :
226 : !Arguments ------------------------------------
227 : !scalars
228 : integer, intent(in) :: ixc
229 : integer, intent(out) :: xclevel
230 : integer, intent(out), optional :: usefock
231 :
232 : !Local variables-------------------------------
233 : integer :: ii,isiz,jj
234 : character(len=500) :: msg
235 :
236 : ! *************************************************************************
237 :
238 63793 : xclevel=0 ; if(present(usefock)) usefock=0
239 63793 : if( ( 1<=ixc .and. ixc<=10).or.(30<=ixc .and. ixc<=39).or.(ixc==50) )xclevel=1 ! LDA
240 63793 : if ( ( ixc==51) ) xclevel=1 ! temperature-dependant LDA functionals (TLDA)
241 63793 : if( (11<=ixc .and. ixc<=19).or.(23<=ixc .and. ixc<=29).or. ixc==1402000)xclevel=2 ! GGA
242 63793 : if ( ( ixc==60) ) xclevel=2 ! temperature-dependant GGA functionals (TGGA)
243 63793 : if( 20<=ixc .and. ixc<=22 )xclevel=3 ! ixc for TDDFT kernel tests
244 63793 : if(present(usefock))then
245 63793 : if( ixc>=40 .and. ixc<=42 )usefock=1 ! Hartree-Fock or internal hybrid functionals
246 : endif
247 63793 : if( ixc>=31 .and. ixc<=35)xclevel=2 ! ixc for internal fake mGGA
248 63793 : if( ixc>=41 .and. ixc<=42)xclevel=2 ! ixc for internal hybrids using GGA
249 63793 : if (ixc<0) then ! libXC: metaGGA and hybrid functionals
250 14153 : xclevel=1
251 42459 : do isiz=1,2
252 : ! ixc has ABINIT sign convention
253 : ! ii has Libxc sign convention
254 28306 : if (isiz==1) ii=-ixc/1000
255 28306 : if (isiz==2) ii=-ixc-ii*1000
256 28306 : if (ii<=0) cycle
257 27180 : jj=libxc_functionals_family_from_id(ii)
258 27180 : if (jj==XC_FAMILY_GGA .or.jj==XC_FAMILY_MGGA) xclevel=2
259 27180 : if (jj==XC_FAMILY_HYB_GGA.or.jj==XC_FAMILY_HYB_MGGA) xclevel=2
260 41333 : if (present(usefock)) then
261 27180 : if (libxc_functionals_is_hybrid_from_id(ii)) usefock=1
262 27180 : if (usefock==1) then
263 931 : if (.not.libxc_functionals_gga_from_hybrid(hybrid_id=ii)) then
264 : write(msg, '(a,i8,3a,2i8,2a)' )&
265 0 : 'ixc=',ixc,' (libXC hybrid functional) is presently not allowed.',ch10,&
266 0 : 'ii,jj=',ii,jj,ch10,&
267 0 : 'Action: try another hybrid functional.'
268 0 : ABI_ERROR(msg)
269 : end if
270 : end if
271 : end if
272 : end do
273 : end if
274 :
275 63793 : end subroutine get_xclevel
276 : !!***
277 :
278 : !----------------------------------------------------------------------
279 :
280 : !!****f* m_xcdata/get_auxc_ixc
281 : !! NAME
282 : !! get_auxc_ixc
283 : !!
284 : !! FUNCTION
285 : !! Returns the ixc of an auxiliary XC functional to be used instead of the input ixc
286 : !! For most of the functionals, there is no need of an auxiliary functional, in which case auxc_ixc=0
287 : !! For hybrid functionals, on the contrary, some speedup can be achieved by using such an auxiliary functional
288 : !! Note that this XC functional intend to replace the whole ixc functional. Generally speakin, it should be
289 : !! mistaken for the GGA part of the hybrid functional (that is for exchange only, actually).
290 : !!
291 : !! At present, always return ixc=1, but this might change in the future ...
292 : !!
293 : !! INPUTS
294 : !! ixc= index of exchange-correlation functional
295 : !!
296 : !! OUTPUT
297 : !! auxc_ixc= 0 if no need of an auxiliary functional, otherwise, returns the ixc of an auxiliary functional.
298 : !!
299 : !! SIDE EFFECTS
300 : !!
301 : !! SOURCE
302 :
303 23 : subroutine get_auxc_ixc(auxc_ixc,ixc)
304 :
305 : !Arguments ------------------------------------
306 : !scalars
307 : integer, intent(in) :: ixc
308 : integer, intent(out) :: auxc_ixc
309 :
310 : !Local variables-------------------------------
311 : integer :: usefock,xclevel
312 : !integer :: gga_id(2)
313 :
314 : ! *************************************************************************
315 :
316 23 : auxc_ixc=11
317 : !Native hybrid functionals from ABINIT
318 23 : if (ixc==40.or.ixc==41.or.ixc==42) then
319 : auxc_ixc = 11
320 : !Hybrid functionals from libxc
321 18 : else if (ixc<0) then
322 18 : call get_xclevel(ixc,xclevel,usefock)
323 18 : if(usefock==1)then
324 18 : auxc_ixc=11
325 : ! if (libxc_functionals_gga_from_hybrid(hybrid_id=ixc,gga_id=gga_id)) then
326 : ! auxc_ixc=-gga_id(1)*1000-gga_id(2)
327 : ! endif
328 : end if
329 : end if
330 :
331 23 : end subroutine get_auxc_ixc
332 :
333 0 : end module m_xcdata
334 : !!***
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