build_full_hamiltonian_from_sparse Subroutine

    subroutine build_full_hamiltonian_from_sparse(this, full_ham)
        type(HamiltonianCalcType), intent(inout) :: this
        HElement_t(dp), intent(out) :: full_ham(:, :)
        HElement_t(dp), allocatable :: vec(:)
        integer :: i, ierr
        write(stdout, *) "converting sparse hamiltonian to full"
        safe_malloc(vec, (this%space_size))
        do i = 1, this%space_size
            call MPIBarrier(ierr)
            vec = h_cast(0.0_dp)
            vec(i) = h_cast(1.0_dp)
            if (iprocindex == root) then
                call multiply_hamil_and_vector(this, vec, full_ham(i, 1:this%space_size))
            else
                call multiply_hamil_and_vector(this, vec, this%temp_out)
            end if
            write(stdout, *) i, "hamiltonian columns converted"
            call MPIBarrier(ierr)
        end do
        safe_free(vec)
    end subroutine build_full_hamiltonian_from_sparse