mirror of https://gitlab.com/QEF/q-e.git
75 lines
2.2 KiB
Fortran
75 lines
2.2 KiB
Fortran
!
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! Copyright (C) 2001-2003 PWSCF group
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! This file is distributed under the terms of the
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! GNU General Public License. See the file `License'
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! in the root directory of the present distribution,
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! or http://www.gnu.org/copyleft/gpl.txt .
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!
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!
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!--------------------------------------------------------------------
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subroutine dos_t (et, nspin, nbnd, nks, ntetra, tetra, e, dost)
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!------------------------------------------------------------------
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!
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USE kinds, only : DP
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implicit none
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integer :: nspin, nbnd, nks, ntetra, tetra (4, ntetra)
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real(DP) :: et (nbnd, nks), e, dost (2)
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integer :: itetra (4), nk, ns, nt, ibnd, i
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real(DP) :: etetra (4), e1, e2, e3, e4
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integer :: nspin0, nspin1
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nspin0=nspin
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nspin1=nspin
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if (nspin==4) then
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nspin0=1
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nspin1=2
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endif
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do ns = 1, nspin0
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dost (ns) = 0.d0
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!
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! nk is used to select k-points with up (ns=1) or down (ns=2) spin
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!
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if (ns.eq.1) then
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nk = 0
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else
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nk = nks / 2
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endif
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do nt = 1, ntetra
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do ibnd = 1, nbnd
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! these are the energies at the vertexes of the nt-th tetrahedron
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do i = 1, 4
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etetra (i) = et (ibnd, tetra (i, nt) + nk)
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enddo
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itetra (1) = 0
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call hpsort (4, etetra, itetra)
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e1 = etetra (1)
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e2 = etetra (2)
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e3 = etetra (3)
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e4 = etetra (4)
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if (e.lt.e4.and.e.ge.e3) then
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dost (ns) = dost (ns) + 1.d0 / ntetra * (3.0 * (e4 - e) **2 / &
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(e4 - e1) / (e4 - e2) / (e4 - e3) )
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elseif (e.lt.e3.and.e.ge.e2) then
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dost (ns) = dost (ns) + 1.d0 / ntetra / (e3 - e1) / (e4 - e1) &
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* (3.0 * (e2 - e1) + 6.0 * (e-e2) - 3.0 * (e3 - e1 + e4 - e2) &
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/ (e3 - e2) / (e4 - e2) * (e-e2) **2)
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elseif (e.lt.e2.and.e.gt.e1) then
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dost (ns) = dost (ns) + 1.d0 / ntetra * 3.0 * (e-e1) **2 / &
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(e2 - e1) / (e3 - e1) / (e4 - e1)
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endif
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enddo
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enddo
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! add correct spin normalization : 2 for LDA, 1 for LSDA or
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! noncollinear calculations
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dost (ns) = dost (ns) * 2.d0 / nspin1
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enddo
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return
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end subroutine dos_t
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