init Subroutine

    subroutine init(self)
        class(density_summation), intent(inout) :: self

        select case (spc_obj%density_summation_method)
        case ('continuous')
            self%density => continuous_density_summation
        case ('normalized')
            self%density => normalized_density_summation
        case ('denormalized')
            self%density => denormalized_density_summation
        case default
            self%density => denormalized_density_summation
        end select

    end subroutine init