#ifdef USE_CUTOFF
if (atom1 < NUM_ATOMS && atom2 < NUM_ATOMS && atom1 != atom2 && r2 < CUTOFF_SQUARED) {
#else
if (atom1 < NUM_ATOMS && atom2 < NUM_ATOMS && atom1 != atom2) {
#endif
#ifdef USE_SYMMETRIC
    real tempForce = 0.0f;
#else
    real4 tempForce1 = (real4) 0;
    real4 tempForce2 = (real4) 0;
#endif
    COMPUTE_FORCE
#ifdef USE_SYMMETRIC
    dEdR += tempForce*invR;
#else
    dEdR1 += tempForce1;
    dEdR2 += tempForce2;
#endif
}