TABLE OF CONTENTS
ABINIT/ep_el_weights [ Functions ]
NAME
ep_el_weights
FUNCTION
This routine calculates the Fermi Surface integration weights
for the electron phonon routines, by different methods
1) Gaussian smearing
2) Tetrahedron method
3) Window in bands for all k-points
4) Fermi Dirac smearing, follows gaussian with a different smearing function
COPYRIGHT
Copyright (C) 2010-2018 ABINIT group (MVer) This file is distributed under the terms of the GNU General Public Licence, see ~abinit/COPYING or http://www.gnu.org/copyleft/gpl.txt . For the initials of contributors, see ~abinit/doc/developers/contributors.txt .
INPUTS
ep_b_min = minimal band to include in FS window integration
ep_b_max = maximal band to include in FS window integration
eigenGS = Ground State eigenvalues
elphsmear = smearing width for Gaussian method
fermie = Fermi level
gprimd = Reciprocal lattice vectors (dimensionful)
irredtoGS = mapping of elph k-points to ground state grid
kptrlatt = k-point grid vectors (if divided by determinant of present matrix)
max_occ = maximal occupancy for a band
minFSband = minimal band included for Fermi Surface integration in Gaussian and Tetrahedron cases
nFSband = number of bands in FS integration
nsppol = number of spin polarizations
telphint = option for FS integration:
0 Tetrahedron method
1 Gaussian smearing
2 Window in bands for all k-points
3 Fermi Dirac smearing
k_obj%nkpt = number of FS k-points
k_obj%kpt = FS k-points
k_obj%full2irr = mapping of FS k-points from full grid to irred points
k_obj%full2full = mapping of FS k-points in full grid under symops
OUTPUT
TODO
weights should be recalculated on-the-fly! The present implementation is not flexible!
PARENTS
get_nv_fs_en,get_tau_k
CHILDREN
destroy_tetra,get_tetra_weight,init_tetra,matr3inv
SOURCE
58 #if defined HAVE_CONFIG_H 59 #include "config.h" 60 #endif 61 62 #include "abi_common.h" 63 64 subroutine ep_el_weights(ep_b_min, ep_b_max, eigenGS, elphsmear, enemin, enemax, nene, gprimd, & 65 & irredtoGS, kptrlatt, max_occ, minFSband, nband, nFSband, nsppol, telphint, k_obj, tmp_wtk) 66 67 use defs_basis 68 use defs_elphon 69 use m_profiling_abi 70 use m_errors 71 use m_tetrahedron 72 use m_xmpi 73 74 !This section has been created automatically by the script Abilint (TD). 75 !Do not modify the following lines by hand. 76 #undef ABI_FUNC 77 #define ABI_FUNC 'ep_el_weights' 78 use interfaces_32_util 79 !End of the abilint section 80 81 implicit none 82 83 !Arguments ------------------------------------ 84 !scalars 85 type(elph_kgrid_type), intent(in) :: k_obj 86 integer, intent(in) :: ep_b_min 87 integer, intent(in) :: ep_b_max 88 integer,intent(in) :: nband,nene 89 real(dp), intent(in) :: elphsmear 90 real(dp), intent(in) :: enemin,enemax 91 real(dp), intent(in) :: gprimd(3,3) 92 integer, intent(in) :: kptrlatt(3,3) 93 real(dp), intent(in) :: max_occ 94 integer, intent(in) :: minFSband 95 integer, intent(in) :: nFSband 96 integer, intent(in) :: nsppol 97 integer, intent(in) :: telphint 98 99 ! arrays 100 real(dp), intent(in) :: eigenGS(nband,k_obj%nkptirr,nsppol) 101 real(dp), intent(out) :: tmp_wtk(nFSband,k_obj%nkpt,nsppol,nene) 102 integer, intent(in) :: irredtoGS(k_obj%nkptirr) 103 104 !Local variables------------------------------- 105 !scalars 106 integer,parameter :: bcorr0=0 107 integer :: ikpt, ikptgs, ib1, iband 108 integer :: ierr, ie, isppol 109 real(dp) :: deltaene, rcvol, fermie 110 real(dp) :: smdeltaprefactor, smdeltafactor, xx 111 112 ! arrays 113 real(dp) :: rlatt(3,3), klatt(3,3) 114 real(dp), allocatable :: tmp_eigen(:), tweight(:,:), dtweightde(:,:) 115 character (len=500) :: message 116 character (len=80) :: errstr 117 type(t_tetrahedron) :: tetrahedra 118 119 ! ************************************************************************* 120 121 ! Initialize tmp_wtk with zeros 122 tmp_wtk = zero 123 124 !write(std_out,*) 'ep_el : nkpt ', k_obj%nkpt 125 !=================================== 126 !Set up integration weights for FS 127 !=================================== 128 deltaene = (enemax-enemin)/dble(nene-1) 129 130 if (telphint == 0) then 131 132 ! ========================= 133 ! Tetrahedron integration 134 ! ========================= 135 136 rlatt(:,:) = kptrlatt(:,:) 137 call matr3inv(rlatt,klatt) 138 139 call init_tetra(k_obj%full2full(1,1,:), gprimd,klatt,k_obj%kpt, k_obj%nkpt,& 140 & tetrahedra, ierr, errstr) 141 ABI_CHECK(ierr==0,errstr) 142 143 rcvol = abs (gprimd(1,1)*(gprimd(2,2)*gprimd(3,3)-gprimd(3,2)*gprimd(2,3)) & 144 & -gprimd(2,1)*(gprimd(1,2)*gprimd(3,3)-gprimd(3,2)*gprimd(1,3)) & 145 & +gprimd(3,1)*(gprimd(1,2)*gprimd(2,3)-gprimd(2,2)*gprimd(1,3))) 146 147 ! fix small window around fermie for tetrahedron weight calculation 148 deltaene = (enemax-enemin)/dble(nene-1) 149 150 ABI_ALLOCATE(tmp_eigen,(k_obj%nkpt)) 151 ABI_ALLOCATE(tweight,(k_obj%nkpt,nene)) 152 ABI_ALLOCATE(dtweightde,(k_obj%nkpt,nene)) 153 154 do iband = 1,nFSband 155 ! for each spin pol 156 do isppol=1,nsppol 157 ! For this band get its contribution 158 tmp_eigen(:) = zero 159 do ikpt=1,k_obj%nkpt 160 ikptgs = irredtoGS(k_obj%full2irr(1,ikpt)) 161 tmp_eigen(ikpt) = eigenGS(minFSband+iband-1,ikptgs,isppol) 162 end do 163 ! calculate general integration weights at each irred kpoint as in Blochl et al PRB 49 16223 164 call get_tetra_weight(tmp_eigen,enemin,enemax,& 165 & max_occ,nene,k_obj%nkpt,tetrahedra,bcorr0,& 166 & tweight,dtweightde,xmpi_comm_self) 167 168 tmp_wtk(iband,:,isppol,:) = dtweightde(:,:)*k_obj%nkpt 169 end do 170 end do 171 ABI_DEALLOCATE(tmp_eigen) 172 ABI_DEALLOCATE(tweight) 173 ABI_DEALLOCATE(dtweightde) 174 175 call destroy_tetra(tetrahedra) 176 177 else if (telphint == 1) then 178 179 ! ============================================================== 180 ! Gaussian or integration: 181 ! Each kpt contributes a gaussian of integrated weight 1 182 ! for each band. The gaussian being centered at the Fermi level. 183 ! =============================================================== 184 185 ! took out factor 1/k_obj%nkpt which intervenes only at integration time 186 187 ! MJV 18/5/2008 does smdeltaprefactor need to contain max_occ? 188 189 ! gaussian smdeltaprefactor = sqrt(piinv)/elphsmear/k_obj%nkpt 190 smdeltaprefactor = max_occ*sqrt(piinv)/elphsmear 191 smdeltafactor = one/elphsmear 192 193 ! SPPOL loop on isppol as well to get 2 sets of weights 194 do isppol=1,nsppol 195 fermie = enemin 196 do ie = 1, nene 197 fermie = fermie + deltaene 198 ! fine grid 199 do ikpt=1, k_obj%nkpt 200 ikptgs = irredtoGS(k_obj%full2irr(1,ikpt)) 201 do ib1=1,nFSband 202 xx = smdeltafactor*(eigenGS(minFSband-1+ib1,ikptgs,isppol) - fermie) 203 if (abs(xx) < 40._dp) then 204 tmp_wtk(ib1,ikpt,isppol,ie) = exp(-xx*xx)*smdeltaprefactor 205 end if 206 end do 207 end do 208 end do 209 end do 210 211 212 else if (telphint == 2) then ! range of bands occupied 213 214 ! SPPOL eventually be able to specify bands for up and down separately 215 fermie = enemin 216 do ie = 1, nene 217 fermie = fermie + deltaene 218 do ikpt=1,k_obj%nkpt 219 do ib1=ep_b_min, ep_b_max 220 ! for the moment both spin channels same 221 tmp_wtk(ib1,ikpt,:,ie) = max_occ 222 end do 223 end do 224 end do 225 226 write(std_out,*) ' ep_el_weights : DOS is calculated from states in bands ',ep_b_min,' to ',ep_b_max 227 228 else if (telphint == 3) then 229 230 ! ============================================================== 231 ! Fermi Dirac integration: 232 ! Each kpt contributes a Fermi Dirac smearing function of integrated weight 1 233 ! for each band. The function being centered at the Fermi level. 234 ! =============================================================== 235 236 ! took out factor 1/k_obj%nkpt which intervenes only at integration time 237 238 ! MJV 18/5/2008 does smdeltaprefactor need to contain max_occ? 239 240 ! gaussian smdeltaprefactor = sqrt(piinv)/elphsmear/k_obj%nkpt 241 smdeltaprefactor = half*max_occ/elphsmear 242 smdeltafactor = one/elphsmear 243 244 ! SPPOL loop on isppol as well to get 2 sets of weights 245 do isppol=1,nsppol 246 fermie = enemin 247 do ie = 1, nene 248 fermie = fermie + deltaene 249 ! fine grid 250 do ikpt=1, k_obj%nkpt 251 ikptgs = irredtoGS(k_obj%full2irr(1,ikpt)) 252 do ib1=1,nFSband 253 xx = smdeltafactor*(eigenGS(minFSband-1+ib1,ikptgs,isppol) - fermie) 254 tmp_wtk(ib1,ikpt,isppol,ie) = smdeltaprefactor / (one + cosh(xx)) 255 end do 256 end do 257 end do 258 end do 259 260 261 else 262 write (message,'(a,i0)')" telphint should be between 0 and 3, found: ",telphint 263 MSG_BUG(message) 264 end if ! if telphint 265 266 267 end subroutine ep_el_weights