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qp2/src/utils_trust_region/sub_to_full_rotation_matrix.irp.f

65 lines
2.1 KiB
Fortran

! Rotation matrix in a subspace to rotation matrix in the full space
! Usually, we are using a list of MOs, for exemple the active ones. When
! we compute a rotation matrix to rotate the MOs, we just compute a
! rotation matrix for these MOs in order to reduce the size of the
! matrix which has to be computed. Since the computation of a rotation
! matrix scale in $O(N^3)$ with $N$ the number of MOs, it's better to
! reuce the number of MOs involved.
! After that we replace the rotation matrix in the full space by
! building the elements of the rotation matrix in the full space from
! the elements of the rotation matrix in the subspace and adding some 0
! on the extradiagonal elements and some 1 on the diagonal elements,
! for the MOs that are not involved in the rotation.
! Provided:
! | mo_num | integer | Number of MOs |
! Input:
! | m | integer | Size of tmp_list, m <= mo_num |
! | tmp_list(m) | integer | List of MOs |
! | tmp_R(m,m) | double precision | Rotation matrix in the space of |
! | | | the MOs containing by tmp_list |
! Output:
! | R(mo_num,mo_num | double precision | Rotation matrix in the space |
! | | | of all the MOs |
! Internal:
! | i,j | integer | indexes in the full space |
! | tmp_i,tmp_j | integer | indexes in the subspace |
subroutine sub_to_full_rotation_matrix(m,tmp_list,tmp_R,R)
!BEGIN_DOC
! Compute the full rotation matrix from a smaller one
!END_DOC
implicit none
! in
integer, intent(in) :: m, tmp_list(m)
double precision, intent(in) :: tmp_R(m,m)
! out
double precision, intent(out) :: R(mo_num,mo_num)
! internal
integer :: i,j,tmp_i,tmp_j
! tmp_R to R, subspace to full space
R = 0d0
do i = 1, mo_num
R(i,i) = 1d0 ! 1 on the diagonal because it is a rotation matrix, 1 = nothing change for the corresponding orbital
enddo
do tmp_j = 1, m
j = tmp_list(tmp_j)
do tmp_i = 1, m
i = tmp_list(tmp_i)
R(i,j) = tmp_R(tmp_i,tmp_j)
enddo
enddo
end