setupBreathingCont Subroutine

    subroutine setupBreathingCont(prefactor)
        implicit none
        integer :: li(3), i, kx, ky, kz, q(3), s
        real(dp) :: bcBuf, prefactor
        do i = 1, 3
            li(i) = nBasisMax(i, 2) - nBasisMax(i, 1) + 1
        end do
        allocate(breathingCont(li(1) * li(2) * li(3) * 2), stat=s)
        do s = 1, 2
            do kz = 1, li(3)
                do ky = 1, li(2)
                    do kx = 1, li(1)
                        ! momentum is the only input to the matrix elements of the breathing
                        ! contribution
                        q = (/kx, ky, kz/)
                        call MomPbcSym(q, nBasisMax)
                        bcBuf = 0.0_dp
                        do i = 1, 3
                            if (li(i) > 1) bcBuf = bcBuf + cos(2 * pi / li(i) * q(i))
                        end do
                        breathingCont(momIndexTable(kx, ky, kz, s)) = prefactor * bcBuf
                    end do
                end do
            end do
        end do
    end subroutine setupBreathingCont