DO I = 1, N - 1
            DO J = I + 1, N
                DX = RX(J) - RX(I)
                DY = RY(J) - RY(I)
                DZ = RZ(J) - RZ(I)

                DX = DX - ANINT(DX / BOX) * BOX
                DY = DY - ANINT(DY / BOX) * BOX
                DZ = DZ - ANINT(DZ / BOX) * BOX

                D = DX ** 2 + DY ** 2 + DZ ** 2

                IF (D .GE. RCUTSQ) THEN
                    CONTINUE
                END IF

                SR2 = SIGMASQ / D
                SR6 = SR2 * SR2 * SR2
                SR12 = SR6 * SR6
                VIJ = SR12 - SR6
                WIJ = VIJ + SR12
                FIJ = WIJ * SR2

                FX(I) = FX(I) + FIJ * DX
                FY(I) = FY(I) + FIJ * DY
                FZ(I) = FZ(I) + FIJ * DZ
                FX(J) = FX(J) - FIJ * DX
                FY(J) = FY(J) - FIJ * DY
                FZ(J) = FZ(J) - FIJ * DZ

                V = V + VIJ
                W = W + WIJ

                NCUT = NCUT + 1
            END DO
        END DO