mirror of
https://github.com/QuantumPackage/qp2.git
synced 2024-10-04 23:25:57 +02:00
166 lines
6.1 KiB
Fortran
166 lines
6.1 KiB
Fortran
subroutine example_determinants
|
||
use bitmasks ! you need to include the bitmasks_module.f90 features
|
||
implicit none
|
||
BEGIN_DOC
|
||
! subroutine that illustrates the main features available in determinants
|
||
END_DOC
|
||
print*,'a determinant is stored as a binary representation of the occupancy of the spatial orbitals'
|
||
print*,'see the bitmask module for more information about that '
|
||
print*,'a spin determinant is an array of (N_int) integers of type bit_kind (see bitmask for more information)'
|
||
print*,'A determinant containing alpha and beta electrons is an array of dimension (2,N_int)'
|
||
integer(bit_kind), allocatable :: det_i(:,:)
|
||
allocate(det_i(N_int,2))
|
||
print*,'det_i(1,:) alpha spins '
|
||
print*,'det_i(2,:) beta spins '
|
||
integer :: i,j
|
||
print*,'initialize det_i to an electron occupation corresponding RHF or ROHF: ref_bitmask '
|
||
do i = 1, N_int
|
||
det_i(i,1) = ref_bitmask(i,1)
|
||
det_i(i,2) = ref_bitmask(i,2)
|
||
enddo
|
||
print*,''
|
||
print*,'print a human readable representation of the determinant '
|
||
call print_det(det_i,N_int)
|
||
print*,'doing a single excitation on top of det_i'
|
||
integer :: h1,p1,s1,i_ok
|
||
h1 = 1
|
||
p1 = elec_alpha_num + 1
|
||
s1 = 1
|
||
print*,'h1 --> p1 of spin s1'
|
||
print*,'i_ok == +1 : excitation is possible '
|
||
print*,'i_ok == -1 : excitation is NOT possible '
|
||
call do_mono_excitation(det_i,h1,p1,s1,i_ok)
|
||
print*,'h1,p1,s1,i_ok'
|
||
print*, h1,p1,s1,i_ok
|
||
if(i_ok == -1)then
|
||
print*,'excitation was not possible '
|
||
stop
|
||
endif
|
||
call debug_det(det_i,N_int)
|
||
print*,'computing the interaction between ref_determinant and det_i '
|
||
double precision :: h0i,hii,h00
|
||
call i_H_j(det_i,det_i,N_int,h0i)
|
||
print*,' < ref | H | det_i > = ',h0i
|
||
print*,'computing the diagonal Hamiltonian matrix element of det_i '
|
||
call i_H_j(ref_bitmask,det_i,N_int,hii)
|
||
print*,'< det_i | H | det_i > = ',hii
|
||
print*,'computing the first-order coefficient of det_i with H0=EN '
|
||
double precision :: c_i
|
||
call i_H_j(ref_bitmask,ref_bitmask,N_int,h00)
|
||
c_i = h0i/(h00 - hii)
|
||
print*,'c_i^{(1)} = ',c_i
|
||
print*,''
|
||
print*,'doing another single excitation on top of det_i'
|
||
h1 = elec_alpha_num
|
||
p1 = elec_alpha_num + 1
|
||
s1 = 2
|
||
call do_mono_excitation(det_i,h1,p1,s1,i_ok)
|
||
print*,'h1,p1,s1,i_ok'
|
||
print*, h1,p1,s1,i_ok
|
||
call i_H_j(det_i,det_i,N_int,h0i)
|
||
print*,' < ref | H | det_i > = ',h0i
|
||
print*,'computing the diagonal Hamiltonian matrix element of det_i '
|
||
call i_H_j(ref_bitmask,ref_bitmask,N_int,h00)
|
||
c_i = h0i/(h00 - hii)
|
||
print*,'c_i^{(1)} = ',c_i
|
||
print*,''
|
||
print*,'Finding the excitation degree between two arbitrary determinants '
|
||
integer :: exc(0:2,2,2)
|
||
double precision :: phase
|
||
integer :: h2,p2,s2,degree
|
||
call get_excitation_degree(ref_bitmask,det_i,degree,N_int)
|
||
print*,'degree = ',degree
|
||
print*,'Finding the differences in terms of holes and particles, together with the fermionic phase '
|
||
call get_excitation(ref_bitmask,det_i,exc,degree,phase,N_int)
|
||
print*,'Fermionic phase for the excitation from ref_bitmask to det_i'
|
||
print*,phase
|
||
print*,'put the excitation information in a human readable format'
|
||
call decode_exc(exc,degree,h1,p1,h2,p2,s1,s2)
|
||
print*,'s1',s1
|
||
print*,'h1,p1 = ',h1,p1
|
||
print*,'s2',s2
|
||
print*,'h2,p2 = ',h2,p2
|
||
print*,''
|
||
print*,'Finding the occupancy of det_i'
|
||
integer, allocatable :: occ(:,:)
|
||
integer :: n_occ_ab(2)
|
||
allocate(occ(N_int*bit_kind_size,2))
|
||
call bitstring_to_list_ab(det_i, occ, n_occ_ab, N_int)
|
||
print*,'alpha electrons orbital occupancy'
|
||
do i = 1, n_occ_ab(1) ! browsing the alpha electrons
|
||
print*,occ(i,1)
|
||
enddo
|
||
print*,'beta electrons orbital occupancy'
|
||
do i = 1, n_occ_ab(2) ! browsing the beta electrons
|
||
print*,occ(i,2)
|
||
enddo
|
||
end
|
||
|
||
|
||
subroutine example_determinants_psi_det
|
||
use bitmasks ! you need to include the bitmasks_module.f90 features
|
||
implicit none
|
||
BEGIN_DOC
|
||
! subroutine that illustrates the main features available in determinants using the psi_det/psi_coef
|
||
END_DOC
|
||
read_wf = .True.
|
||
touch read_wf
|
||
! you force the wave function to be set to the one in the EZFIO folder
|
||
call routine_example_psi_det
|
||
end
|
||
|
||
subroutine routine_example_psi_det
|
||
use bitmasks ! you need to include the bitmasks_module.f90 features
|
||
implicit none
|
||
BEGIN_DOC
|
||
! subroutine that illustrates the main features available in determinants using many determinants
|
||
END_DOC
|
||
integer :: i,j
|
||
integer, allocatable :: degree_list(:)
|
||
integer, allocatable :: idx(:)
|
||
allocate(degree_list(N_det),idx(0:N_det))
|
||
|
||
print*,'Number of determinants in the wave function'
|
||
print*,'N_det = ',N_det
|
||
print*,''
|
||
print*,'Printing in a human readable format all Slater determinants '
|
||
do i = 1, N_det
|
||
call debug_det(psi_det(1,1,i),N_int)
|
||
enddo
|
||
print*,''
|
||
print*,'Number of states computed '
|
||
print*,'N_states = ',N_states
|
||
print*,'Printing the coefficients for all states for all Slater determinants '
|
||
do j = 1, N_states
|
||
print*,'State = ',j
|
||
do i = 1, N_det
|
||
write(*,'(I9,X,F16.10)')i,psi_coef(i,j)
|
||
enddo
|
||
enddo
|
||
print*,''
|
||
print*,'Finding the connection through a two-electron operator in the wave function'
|
||
print*,'You want to know the connections of the first determinant '
|
||
! wave function determinant exc degree list
|
||
call get_excitation_degree_vector( psi_det , psi_det(1,1,1),degree_list,N_int,N_det,idx)
|
||
double precision :: hij
|
||
double precision, allocatable :: i_H_psi(:)
|
||
allocate(i_H_psi(N_states))
|
||
i_H_psi = 0.d0
|
||
print*,'Computing <psi_det(1) | H | psi_det > = \sum_I c_I <psi_det(1)| H | psi_det(I)>'
|
||
do i = 1, idx(0) ! number of Slater determinants connected to the first one
|
||
print*,'Determinant connected'
|
||
call debug_det(psi_det(1,1,idx(i)),N_int)
|
||
print*,'excitation degree = ',degree_list(i)
|
||
call i_H_j(psi_det(1,1,1) , psi_det(1,1,idx(i)),hij,N_int)
|
||
do j = 1, N_states
|
||
i_H_psi(j) += hij * psi_coef(idx(i),j)
|
||
enddo
|
||
enddo
|
||
print*,'i_H_psi = ',i_H_psi
|
||
end
|
||
|
||
|
||
|
||
|
||
|