TABLE OF CONTENTS
ABINIT/ep_fs_weights [ Functions ]
NAME
ep_fs_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
k_obj%wtk = integration weights
TODO
weights should be recalculated on-the-fly! The present implementation is not flexible!
PARENTS
elphon,get_nv_fs_en,get_nv_fs_temp
CHILDREN
destroy_tetra,get_tetra_weight,init_tetra,matr3inv,wrtout
SOURCE
59 #if defined HAVE_CONFIG_H 60 #include "config.h" 61 #endif 62 63 #include "abi_common.h" 64 65 subroutine ep_fs_weights(ep_b_min, ep_b_max, eigenGS, elphsmear, fermie, gprimd, & 66 & irredtoGS, kptrlatt, max_occ, minFSband, nband, nFSband, nsppol, telphint, k_obj) 67 68 69 use defs_basis 70 use defs_elphon 71 use m_profiling_abi 72 use m_xmpi 73 use m_errors 74 use m_xmpi 75 use m_tetrahedron 76 77 !This section has been created automatically by the script Abilint (TD). 78 !Do not modify the following lines by hand. 79 #undef ABI_FUNC 80 #define ABI_FUNC 'ep_fs_weights' 81 use interfaces_14_hidewrite 82 use interfaces_32_util 83 !End of the abilint section 84 85 implicit none 86 87 !Arguments ------------------------------------ 88 !scalars 89 type(elph_kgrid_type), intent(inout) :: k_obj 90 integer, intent(in) :: ep_b_min 91 integer, intent(in) :: ep_b_max 92 integer,intent(in) :: nband 93 real(dp), intent(in) :: elphsmear 94 real(dp), intent(in) :: fermie 95 real(dp), intent(in) :: gprimd(3,3) 96 integer, intent(in) :: kptrlatt(3,3) 97 real(dp), intent(in) :: max_occ 98 integer, intent(in) :: minFSband 99 integer, intent(in) :: nFSband 100 integer, intent(in) :: nsppol 101 integer, intent(in) :: telphint 102 103 ! arrays 104 real(dp), intent(in) :: eigenGS(nband,k_obj%nkptirr,nsppol) 105 integer, intent(in) :: irredtoGS(k_obj%nkptirr) 106 107 !Local variables------------------------------- 108 !scalars 109 integer,parameter :: bcorr0=0 110 integer :: ikpt, ikptgs, ib1, isppol, iband 111 integer :: nene, ifermi 112 integer :: ierr 113 114 real(dp) :: enemin, enemax, deltaene, rcvol 115 real(dp) :: smdeltaprefactor, smdeltafactor, xx 116 117 ! arrays 118 real(dp) :: rlatt(3,3), klatt(3,3) 119 real(dp), allocatable :: tmp_eigen(:), tweight(:,:), dtweightde(:,:) 120 121 character (len=500) :: message 122 character (len=80) :: errstr 123 124 type(t_tetrahedron) :: tetrahedra 125 126 ! ************************************************************************* 127 128 write(std_out,*) 'ep_fs : nkpt ', k_obj%nkpt 129 write(message, '(a)' ) '- ep_fs_weights 1 = ' 130 call wrtout(std_out,message,'PERS') 131 132 !=================================== 133 !Set up integration weights for FS 134 !=================================== 135 136 if (telphint == 0) then 137 138 ! ========================= 139 ! Tetrahedron integration 140 ! ========================= 141 142 rlatt(:,:) = kptrlatt(:,:) 143 call matr3inv(rlatt,klatt) 144 145 call init_tetra(k_obj%full2full(1,1,:), gprimd,klatt,k_obj%kpt, k_obj%nkpt,& 146 & tetrahedra, ierr, errstr) 147 ABI_CHECK(ierr==0,errstr) 148 149 rcvol = abs (gprimd(1,1)*(gprimd(2,2)*gprimd(3,3)-gprimd(3,2)*gprimd(2,3)) & 150 & -gprimd(2,1)*(gprimd(1,2)*gprimd(3,3)-gprimd(3,2)*gprimd(1,3)) & 151 & +gprimd(3,1)*(gprimd(1,2)*gprimd(2,3)-gprimd(2,2)*gprimd(1,3))) 152 153 ! just do weights at FS 154 nene = 100 155 156 ! fix small window around fermie for tetrahedron weight calculation 157 deltaene = 2*elphsmear/dble(nene-1) 158 ifermi = int(nene/2) 159 enemin = fermie - dble(ifermi-1)*deltaene 160 enemax = enemin + dble(nene-1)*deltaene 161 162 ABI_ALLOCATE(tmp_eigen,(k_obj%nkpt)) 163 ABI_ALLOCATE(tweight,(k_obj%nkpt,nene)) 164 ABI_ALLOCATE(dtweightde,(k_obj%nkpt,nene)) 165 166 do iband = 1,nFSband 167 ! for each spin pol 168 do isppol=1,nsppol 169 ! For this band get its contribution 170 tmp_eigen(:) = zero 171 do ikpt=1,k_obj%nkpt 172 ikptgs = irredtoGS(k_obj%full2irr(1,ikpt)) 173 tmp_eigen(ikpt) = eigenGS(minFSband+iband-1,ikptgs,isppol) 174 end do 175 ! calculate general integration weights at each irred kpoint as in Blochl et al PRB 49 16223 176 177 call get_tetra_weight(tmp_eigen,enemin,enemax,& 178 & max_occ,nene,k_obj%nkpt,tetrahedra,bcorr0,& 179 & tweight,dtweightde,xmpi_comm_self) 180 181 k_obj%wtk(iband,:,isppol) = dtweightde(:,ifermi)*k_obj%nkpt 182 end do 183 184 end do 185 ABI_DEALLOCATE(tmp_eigen) 186 ABI_DEALLOCATE(tweight) 187 ABI_DEALLOCATE(dtweightde) 188 189 call destroy_tetra(tetrahedra) 190 191 else if (telphint == 1) then 192 193 ! ============================================================== 194 ! Gaussian or integration: 195 ! Each kpt contributes a gaussian of integrated weight 1 196 ! for each band. The gaussian being centered at the Fermi level. 197 ! =============================================================== 198 199 ! took out factor 1/k_obj%nkpt which intervenes only at integration time 200 201 ! MJV 18/5/2008 does smdeltaprefactor need to contain max_occ? 202 203 ! gaussian smdeltaprefactor = sqrt(piinv)/elphsmear/k_obj%nkpt 204 smdeltaprefactor = max_occ*sqrt(piinv)/elphsmear 205 smdeltafactor = one/elphsmear 206 207 k_obj%wtk = zero 208 ! SPPOL loop on isppol as well to get 2 sets of weights 209 do isppol=1,nsppol 210 ! fine grid 211 do ikpt=1, k_obj%nkpt 212 ikptgs = irredtoGS(k_obj%full2irr(1,ikpt)) 213 do ib1=1,nFSband 214 xx = smdeltafactor*(eigenGS(minFSband-1+ib1,ikptgs,isppol) - fermie) 215 if (abs(xx) < 40._dp) then 216 k_obj%wtk(ib1,ikpt,isppol) = exp(-xx*xx)*smdeltaprefactor 217 end if 218 end do 219 end do 220 end do 221 222 223 else if (telphint == 2) then ! range of bands occupied 224 225 ! SPPOL eventually be able to specify bands for up and down separately 226 k_obj%wtk = zero 227 do ikpt=1,k_obj%nkpt 228 do ib1=ep_b_min, ep_b_max 229 ! for the moment both spin channels same 230 k_obj%wtk(ib1,ikpt,:) = max_occ 231 end do 232 end do 233 234 write(std_out,*) ' ep_fs_weights : DOS is calculated from states in bands ',ep_b_min,' to ',ep_b_max 235 236 else if (telphint == 3) then 237 238 ! ============================================================== 239 ! Fermi Dirac integration: 240 ! Each kpt contributes a Fermi Dirac smearing function of integrated weight 1 241 ! for each band. The function being centered at the Fermi level. 242 ! =============================================================== 243 244 ! took out factor 1/k_obj%nkpt which intervenes only at integration time 245 246 ! MJV 18/5/2008 does smdeltaprefactor need to contain max_occ? 247 248 ! gaussian smdeltaprefactor = sqrt(piinv)/elphsmear/k_obj%nkpt 249 smdeltaprefactor = half*max_occ/elphsmear 250 smdeltafactor = one/elphsmear 251 252 k_obj%wtk = zero 253 ! SPPOL loop on isppol as well to get 2 sets of weights 254 do isppol=1,nsppol 255 ! fine grid 256 do ikpt=1, k_obj%nkpt 257 ikptgs = irredtoGS(k_obj%full2irr(1,ikpt)) 258 do ib1=1,nFSband 259 xx = smdeltafactor*(eigenGS(minFSband-1+ib1,ikptgs,isppol) - fermie) 260 k_obj%wtk(ib1,ikpt,isppol) = smdeltaprefactor / (one + cosh(xx)) 261 end do 262 end do 263 end do 264 265 266 else 267 write (message,'(a,i0)')" telphint should be between 0 and 3, found: ",telphint 268 MSG_BUG(message) 269 end if ! if telphint 270 271 272 end subroutine ep_fs_weights