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194 lines
5.6 KiB
Fortran
194 lines
5.6 KiB
Fortran
subroutine get_excitation_general(key_i,key_j, Nint,degree_array,holes_array, particles_array,phase)
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use bitmasks
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BEGIN_DOC
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! returns the array, for each spin, of holes/particles between key_i and key_j
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!
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! with the following convention: a^+_{particle} a_{hole}|key_i> = |key_j>
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END_DOC
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include 'utils/constants.include.F'
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implicit none
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integer, intent(in) :: Nint
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integer(bit_kind), intent(in) :: key_j(Nint,2),key_i(Nint,2)
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integer, intent(out) :: holes_array(100,2),particles_array(100,2),degree_array(2)
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double precision, intent(out) :: phase
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integer :: ispin,k,i,pos
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integer(bit_kind) :: key_hole, key_particle
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integer(bit_kind) :: xorvec(N_int_max,2)
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holes_array = -1
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particles_array = -1
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degree_array = 0
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do i = 1, N_int
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xorvec(i,1) = xor( key_i(i,1), key_j(i,1))
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xorvec(i,2) = xor( key_i(i,2), key_j(i,2))
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degree_array(1) += popcnt(xorvec(i,1))
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degree_array(2) += popcnt(xorvec(i,2))
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enddo
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degree_array(1) = shiftr(degree_array(1),1)
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degree_array(2) = shiftr(degree_array(2),1)
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do ispin = 1, 2
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k = 1
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!!! GETTING THE HOLES
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do i = 1, N_int
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key_hole = iand(xorvec(i,ispin),key_i(i,ispin))
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do while(key_hole .ne.0_bit_kind)
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pos = trailz(key_hole)
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holes_array(k,ispin) = 1+ bit_kind_size * (i-1) + pos
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key_hole = ibclr(key_hole,pos)
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k += 1
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if(k .gt.100)then
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print*,'WARNING in get_excitation_general'
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print*,'More than a 100-th excitation for spin ',ispin
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print*,'stoping ...'
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stop
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endif
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enddo
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enddo
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enddo
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do ispin = 1, 2
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k = 1
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!!! GETTING THE PARTICLES
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do i = 1, N_int
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key_particle = iand(xor(key_i(i,ispin),key_j(i,ispin)),key_j(i,ispin))
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do while(key_particle .ne.0_bit_kind)
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pos = trailz(key_particle)
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particles_array(k,ispin) = 1+ bit_kind_size * (i-1) + pos
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key_particle = ibclr(key_particle,pos)
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k += 1
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if(k .gt.100)then
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print*,'WARNING in get_excitation_general '
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print*,'More than a 100-th excitation for spin ',ispin
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print*,'stoping ...'
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stop
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endif
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enddo
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enddo
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enddo
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integer :: h,p, i_ok
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integer(bit_kind), allocatable :: det_i(:,:),det_ip(:,:)
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integer :: exc(0:2,2,2)
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double precision :: phase_tmp
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allocate(det_i(Nint,2),det_ip(N_int,2))
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det_i = key_i
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phase = 1.d0
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do ispin = 1, 2
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do i = 1, degree_array(ispin)
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h = holes_array(i,ispin)
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p = particles_array(i,ispin)
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det_ip = det_i
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call do_single_excitation(det_ip,h,p,ispin,i_ok)
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if(i_ok == -1)then
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print*,'excitation was not possible '
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stop
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endif
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call get_single_excitation(det_i,det_ip,exc,phase_tmp,Nint)
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phase *= phase_tmp
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det_i = det_ip
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enddo
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enddo
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end
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subroutine get_holes_general(key_i, key_j,Nint, holes_array)
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use bitmasks
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BEGIN_DOC
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! returns the array, per spin, of holes between key_i and key_j
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!
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! with the following convention: a_{hole}|key_i> --> |key_j>
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END_DOC
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implicit none
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integer, intent(in) :: Nint
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integer(bit_kind), intent(in) :: key_j(Nint,2),key_i(Nint,2)
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integer, intent(out) :: holes_array(100,2)
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integer(bit_kind) :: key_hole
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integer :: ispin,k,i,pos
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holes_array = -1
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do ispin = 1, 2
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k = 1
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do i = 1, N_int
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key_hole = iand(xor(key_i(i,ispin),key_j(i,ispin)),key_i(i,ispin))
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do while(key_hole .ne.0_bit_kind)
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pos = trailz(key_hole)
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holes_array(k,ispin) = 1+ bit_kind_size * (i-1) + pos
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key_hole = ibclr(key_hole,pos)
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k += 1
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if(k .gt.100)then
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print*,'WARNING in get_holes_general'
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print*,'More than a 100-th excitation for spin ',ispin
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print*,'stoping ...'
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stop
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endif
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enddo
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enddo
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enddo
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end
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subroutine get_particles_general(key_i, key_j,Nint,particles_array)
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use bitmasks
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BEGIN_DOC
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! returns the array, per spin, of particles between key_i and key_j
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!
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! with the following convention: a^dagger_{particle}|key_i> --> |key_j>
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END_DOC
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implicit none
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integer, intent(in) :: Nint
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integer(bit_kind), intent(in) :: key_j(Nint,2),key_i(Nint,2)
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integer, intent(out) :: particles_array(100,2)
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integer(bit_kind) :: key_particle
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integer :: ispin,k,i,pos
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particles_array = -1
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do ispin = 1, 2
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k = 1
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do i = 1, N_int
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key_particle = iand(xor(key_i(i,ispin),key_j(i,ispin)),key_j(i,ispin))
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do while(key_particle .ne.0_bit_kind)
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pos = trailz(key_particle)
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particles_array(k,ispin) = 1+ bit_kind_size * (i-1) + pos
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key_particle = ibclr(key_particle,pos)
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k += 1
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if(k .gt.100)then
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print*,'WARNING in get_holes_general'
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print*,'More than a 100-th excitation for spin ',ispin
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print*,'Those are the two determinants'
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call debug_det(key_i, N_int)
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call debug_det(key_j, N_int)
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print*,'stoping ...'
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stop
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endif
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enddo
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enddo
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enddo
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end
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subroutine get_phase_general(key_i,Nint,degree, holes_array, particles_array,phase)
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implicit none
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integer, intent(in) :: degree(2), Nint
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integer(bit_kind), intent(in) :: key_i(Nint,2)
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integer, intent(in) :: holes_array(100,2),particles_array(100,2)
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double precision, intent(out) :: phase
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integer :: i,ispin,h,p, i_ok
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integer(bit_kind), allocatable :: det_i(:,:),det_ip(:,:)
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integer :: exc(0:2,2,2)
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double precision :: phase_tmp
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allocate(det_i(Nint,2),det_ip(N_int,2))
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det_i = key_i
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phase = 1.d0
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do ispin = 1, 2
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do i = 1, degree(ispin)
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h = holes_array(i,ispin)
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p = particles_array(i,ispin)
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det_ip = det_i
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call do_single_excitation(det_ip,h,p,ispin,i_ok)
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if(i_ok == -1)then
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print*,'excitation was not possible '
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stop
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endif
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call get_single_excitation(det_i,det_ip,exc,phase_tmp,Nint)
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phase *= phase_tmp
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det_i = det_ip
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enddo
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enddo
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end
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