diff --git a/src/ASPHERE/pair_resquared.cpp b/src/ASPHERE/pair_resquared.cpp
index 9322425a88..2044b83325 100644
--- a/src/ASPHERE/pair_resquared.cpp
+++ b/src/ASPHERE/pair_resquared.cpp
@@ -778,7 +778,7 @@ double PairRESquared::resquared_analytic(const int i, const int j, const RE2Vars
 
   // torque on j
 
-  if (!(force->newton_pair || j < atom->nlocal)) return Ua + Ur;
+  if (!force->newton_pair && j >= atom->nlocal) return Ua + Ur;
 
   MathExtra::vecmat(fourw, wj.aTe, fwae);
 
diff --git a/src/DIFFRACTION/compute_xrd.cpp b/src/DIFFRACTION/compute_xrd.cpp
index 48152a7f68..010e5bcb7d 100644
--- a/src/DIFFRACTION/compute_xrd.cpp
+++ b/src/DIFFRACTION/compute_xrd.cpp
@@ -125,7 +125,7 @@ ComputeXRD::ComputeXRD(LAMMPS *lmp, int narg, char **arg) :
       if (iarg+2 > narg) error->all(FLERR,"Illegal Compute XRD Command");
       LP = utils::numeric(FLERR,arg[iarg+1],false,lmp);
 
-      if (!(LP == 1 || LP == 0))
+      if (LP != 1 && LP != 0)
          error->all(FLERR,"Compute XRD: LP must have value of 0 or 1");
       iarg += 2;
 
diff --git a/src/ELECTRODE/electrode_matrix.cpp b/src/ELECTRODE/electrode_matrix.cpp
index 5faac5a252..7be9119c62 100644
--- a/src/ELECTRODE/electrode_matrix.cpp
+++ b/src/ELECTRODE/electrode_matrix.cpp
@@ -158,7 +158,7 @@ void ElectrodeMatrix::pair_contribution(double **array)
         aij *= ElectrodeMath::safe_erfc(g_ewald * r);
         aij -= ElectrodeMath::safe_erfc(etaij * r) * rinv;
         // newton on or off?
-        if (!(newton_pair || j < nlocal)) aij *= 0.5;
+        if (!newton_pair && j >= nlocal) aij *= 0.5;
         bigint jpos = tag_to_iele[tag[j]];
         array[ipos][jpos] += aij;
         array[jpos][ipos] += aij;
diff --git a/src/KSPACE/remap.cpp b/src/KSPACE/remap.cpp
index 2b2883e560..57bde0beca 100644
--- a/src/KSPACE/remap.cpp
+++ b/src/KSPACE/remap.cpp
@@ -637,7 +637,7 @@ void remap_3d_destroy_plan(struct remap_plan_3d *plan)
 {
   // free MPI communicator
 
-  if (!((plan->usecollective) && (plan->commringlen == 0)))
+  if (!(plan->usecollective) || (plan->commringlen != 0))
     MPI_Comm_free(&plan->comm);
 
   if (plan->usecollective) {
diff --git a/src/MANYBODY/pair_airebo.cpp b/src/MANYBODY/pair_airebo.cpp
index 6f3706380e..129b9d2218 100644
--- a/src/MANYBODY/pair_airebo.cpp
+++ b/src/MANYBODY/pair_airebo.cpp
@@ -1775,7 +1775,7 @@ double PairAIREBO::bondorder(int i, int j, double rij[3], double rijmag, double
             atoml = REBO_neighs_j[l];
             atom4 = atoml;
             ltype = map[type[atoml]];
-            if (!(atoml == atomi || atoml == atomk)) {
+            if (atoml != atomi && atoml != atomk) {
               r34[0] = x[atom3][0]-x[atom4][0];
               r34[1] = x[atom3][1]-x[atom4][1];
               r34[2] = x[atom3][2]-x[atom4][2];
@@ -2284,7 +2284,7 @@ double PairAIREBO::bondorderLJ(int i, int j, double /* rij_mod */[3], double rij
             atoml = REBO_neighs_j[l];
             atom4 = atoml;
             ltype = map[type[atoml]];
-            if (!(atoml == atomi || atoml == atomk)) {
+            if (atoml != atomi && atoml != atomk) {
               r34[0] = x[atom3][0]-x[atom4][0];
               r34[1] = x[atom3][1]-x[atom4][1];
               r34[2] = x[atom3][2]-x[atom4][2];
@@ -2732,7 +2732,7 @@ double PairAIREBO::bondorderLJ(int i, int j, double /* rij_mod */[3], double rij
               atoml = REBO_neighs_j[l];
               atom4 = atoml;
               ltype = map[type[atoml]];
-              if (!(atoml == atomi || atoml == atomk)) {
+              if (atoml != atomi && atoml != atomk) {
                 r34[0] = x[atom3][0]-x[atom4][0];
                 r34[1] = x[atom3][1]-x[atom4][1];
                 r34[2] = x[atom3][2]-x[atom4][2];
diff --git a/src/MESONT/pair_mesocnt.cpp b/src/MESONT/pair_mesocnt.cpp
index 464d4ba8bc..521c8c5f60 100644
--- a/src/MESONT/pair_mesocnt.cpp
+++ b/src/MESONT/pair_mesocnt.cpp
@@ -481,7 +481,7 @@ void PairMesoCNT::compute(int eflag, int vflag)
           geometry(r1, r2, p1, p2, nullptr, p, m, param, basis);
 
           if (param[0] > cutoff) continue;
-          if (!(param[2] < 0 && param[3] > 0)) {
+          if (param[2] >= 0 || param[3] <= 0) {
             double salpha = sin(param[1]);
             double sxi1 = salpha * param[2];
             double sxi2 = salpha * param[3];
@@ -503,7 +503,7 @@ void PairMesoCNT::compute(int eflag, int vflag)
             geometry(r1, r2, p2, p1, qe, p, m, param, basis);
 
           if (param[0] > cutoff) continue;
-          if (!(param[2] < 0 && param[3] > 0)) {
+          if (param[2] >= 0 || param[3] <= 0) {
             double hsq = param[0] * param[0];
             double calpha = cos(param[1]);
             double etamin = calpha * param[2];
diff --git a/src/MESONT/pair_mesocnt_viscous.cpp b/src/MESONT/pair_mesocnt_viscous.cpp
index 10ce8b8344..be3715be25 100644
--- a/src/MESONT/pair_mesocnt_viscous.cpp
+++ b/src/MESONT/pair_mesocnt_viscous.cpp
@@ -485,7 +485,7 @@ void PairMesoCNTViscous::compute(int eflag, int vflag)
           geometry(r1, r2, p1, p2, nullptr, p, m, param, basis);
 
           if (param[0] > cutoff) continue;
-          if (!(param[2] < 0 && param[3] > 0)) {
+          if (param[2] >= 0 || param[3] <= 0) {
             double salpha = sin(param[1]);
             double sxi1 = salpha * param[2];
             double sxi2 = salpha * param[3];
@@ -508,7 +508,7 @@ void PairMesoCNTViscous::compute(int eflag, int vflag)
             geometry(r1, r2, p2, p1, qe, p, m, param, basis);
 
           if (param[0] > cutoff) continue;
-          if (!(param[2] < 0 && param[3] > 0)) {
+          if (param[2] >= 0 || param[3] <= 0) {
             double hsq = param[0] * param[0];
             double calpha = cos(param[1]);
             double etamin = calpha * param[2];
diff --git a/src/OPENMP/pair_airebo_omp.cpp b/src/OPENMP/pair_airebo_omp.cpp
index f5cd8ffd9d..0872678518 100644
--- a/src/OPENMP/pair_airebo_omp.cpp
+++ b/src/OPENMP/pair_airebo_omp.cpp
@@ -1546,7 +1546,7 @@ double PairAIREBOOMP::bondorder_thr(int i, int j, double rij[3], double rijmag,
             atoml = REBO_neighs_j[l];
             atom4 = atoml;
             ltype = map[type[atoml]];
-            if (!(atoml == atomi || atoml == atomk)) {
+            if (atoml != atomi && atoml != atomk) {
               r34[0] = x[atom3][0]-x[atom4][0];
               r34[1] = x[atom3][1]-x[atom4][1];
               r34[2] = x[atom3][2]-x[atom4][2];
@@ -2048,7 +2048,7 @@ double PairAIREBOOMP::bondorderLJ_thr(int i, int j, double /* rij_mod */[3], dou
             atoml = REBO_neighs_j[l];
             atom4 = atoml;
             ltype = map[type[atoml]];
-            if (!(atoml == atomi || atoml == atomk)) {
+            if (atoml != atomi && atoml != atomk) {
               r34[0] = x[atom3][0]-x[atom4][0];
               r34[1] = x[atom3][1]-x[atom4][1];
               r34[2] = x[atom3][2]-x[atom4][2];
@@ -2496,7 +2496,7 @@ double PairAIREBOOMP::bondorderLJ_thr(int i, int j, double /* rij_mod */[3], dou
               atoml = REBO_neighs_j[l];
               atom4 = atoml;
               ltype = map[type[atoml]];
-              if (!(atoml == atomi || atoml == atomk)) {
+              if (atoml != atomi && atoml != atomk) {
                 r34[0] = x[atom3][0]-x[atom4][0];
                 r34[1] = x[atom3][1]-x[atom4][1];
                 r34[2] = x[atom3][2]-x[atom4][2];
diff --git a/src/REACTION/fix_bond_react.cpp b/src/REACTION/fix_bond_react.cpp
index eaf4dfd0ec..784c163f70 100644
--- a/src/REACTION/fix_bond_react.cpp
+++ b/src/REACTION/fix_bond_react.cpp
@@ -1358,7 +1358,7 @@ void FixBondReact::superimpose_algorithm()
 
 
       int hang_catch = 0;
-      while (!(status == ACCEPT || status == REJECT)) {
+      while (status != ACCEPT && status != REJECT) {
 
         for (int i = 0; i < max_natoms; i++) {
           pioneers[i] = 0;
@@ -4176,7 +4176,7 @@ void FixBondReact::ReadConstraints(char *line, int myrxn)
       tmp[3] = 182.0;
       rv = sscanf(line,"%*s %s %s %s %s %lg %lg %lg %lg",strargs[0],strargs[1],
              strargs[2],strargs[3],&tmp[0],&tmp[1],&tmp[2],&tmp[3]);
-      if (!(rv == 6 || rv == 8)) error->one(FLERR, "Dihedral constraint is incorrectly formatted");
+      if (rv != 6 && rv != 8) error->one(FLERR, "Dihedral constraint is incorrectly formatted");
       readID(strargs[0], i, myrxn, 0);
       readID(strargs[1], i, myrxn, 1);
       readID(strargs[2], i, myrxn, 2);
@@ -4198,7 +4198,7 @@ void FixBondReact::ReadConstraints(char *line, int myrxn)
       constraints[i][myrxn].type = RMSD;
       strcpy(strargs[0],"0");
       rv = sscanf(line,"%*s %lg %s",&tmp[0],strargs[0]);
-      if (!(rv == 1 || rv == 2)) error->one(FLERR, "RMSD constraint is incorrectly formatted");
+      if (rv != 1 && rv != 2) error->one(FLERR, "RMSD constraint is incorrectly formatted");
       constraints[i][myrxn].par[0] = tmp[0]; // RMSDmax
       constraints[i][myrxn].id[0] = -1; // optional molecule fragment
       if (isalpha(strargs[0][0])) {
diff --git a/src/REPLICA/fix_neb.cpp b/src/REPLICA/fix_neb.cpp
index 1ef3019b92..f2962d9b9d 100644
--- a/src/REPLICA/fix_neb.cpp
+++ b/src/REPLICA/fix_neb.cpp
@@ -804,7 +804,7 @@ Calculate ideal positions for parallel "ideal" or "equal"
 void FixNEB::calculate_ideal_positions()
 {
   // Skip unless "ideal" or "equal"
-  if (!((neb_mode == IDEAL) || (neb_mode == EQUAL))) return;
+  if ((neb_mode != IDEAL) && (neb_mode != EQUAL)) return;
 
   double lentot, lenuntilClimber;
   double meanDist, meanDistBeforeClimber, meanDistAfterClimber;
diff --git a/src/RIGID/fix_rattle.cpp b/src/RIGID/fix_rattle.cpp
index 0027b537ee..5a85902609 100644
--- a/src/RIGID/fix_rattle.cpp
+++ b/src/RIGID/fix_rattle.cpp
@@ -831,10 +831,10 @@ bool FixRattle::check2(double **v, int m, bool checkr, bool checkv)
   domain->minimum_image(r01);
   MathExtra::sub3(v[i1],v[i0],v01);
 
-  stat = !(checkr && (fabs(sqrt(MathExtra::dot3(r01,r01)) - bond1) > tol));
+  stat = !checkr || (fabs(sqrt(MathExtra::dot3(r01,r01)) - bond1) <= tol);
   if (!stat) error->one(FLERR,"Coordinate constraints are not satisfied up to desired tolerance ");
 
-  stat = !(checkv && (fabs(MathExtra::dot3(r01,v01)) > tol));
+  stat = !checkv || (fabs(MathExtra::dot3(r01,v01)) <= tol);
   if (!stat) error->one(FLERR,"Velocity constraints are not satisfied up to desired tolerance ");
   return stat;
 }
@@ -863,12 +863,12 @@ bool FixRattle::check3(double **v, int m, bool checkr, bool checkv)
   MathExtra::sub3(v[i1],v[i0],v01);
   MathExtra::sub3(v[i2],v[i0],v02);
 
-  stat = !(checkr && (fabs(sqrt(MathExtra::dot3(r01,r01)) - bond1) > tol ||
-                      fabs(sqrt(MathExtra::dot3(r02,r02))-bond2) > tol));
+  stat = !checkr || (fabs(sqrt(MathExtra::dot3(r01,r01)) - bond1) <= tol &&
+                      fabs(sqrt(MathExtra::dot3(r02,r02))-bond2) <= tol);
   if (!stat) error->one(FLERR,"Coordinate constraints are not satisfied up to desired tolerance ");
 
-  stat = !(checkv && (fabs(MathExtra::dot3(r01,v01)) > tol ||
-                      fabs(MathExtra::dot3(r02,v02)) > tol));
+  stat = !checkv || (fabs(MathExtra::dot3(r01,v01)) <= tol &&
+                      fabs(MathExtra::dot3(r02,v02)) <= tol);
   if (!stat) error->one(FLERR,"Velocity constraints are not satisfied up to desired tolerance ");
   return stat;
 }
@@ -901,14 +901,14 @@ bool FixRattle::check4(double **v, int m, bool checkr, bool checkv)
   MathExtra::sub3(v[i2],v[i0],v02);
   MathExtra::sub3(v[i3],v[i0],v03);
 
-  stat = !(checkr && (fabs(sqrt(MathExtra::dot3(r01,r01)) - bond1) > tol ||
-                      fabs(sqrt(MathExtra::dot3(r02,r02))-bond2) > tol ||
-                      fabs(sqrt(MathExtra::dot3(r03,r03))-bond3) > tol));
+  stat = !checkr || (fabs(sqrt(MathExtra::dot3(r01,r01)) - bond1) <= tol &&
+                      fabs(sqrt(MathExtra::dot3(r02,r02))-bond2) <= tol &&
+                      fabs(sqrt(MathExtra::dot3(r03,r03))-bond3) <= tol);
   if (!stat) error->one(FLERR,"Coordinate constraints are not satisfied up to desired tolerance ");
 
-  stat = !(checkv && (fabs(MathExtra::dot3(r01,v01)) > tol ||
-                      fabs(MathExtra::dot3(r02,v02)) > tol ||
-                      fabs(MathExtra::dot3(r03,v03)) > tol));
+  stat = !checkv || (fabs(MathExtra::dot3(r01,v01)) <= tol &&
+                      fabs(MathExtra::dot3(r02,v02)) <= tol &&
+                      fabs(MathExtra::dot3(r03,v03)) <= tol);
   if (!stat) error->one(FLERR,"Velocity constraints are not satisfied up to desired tolerance ");
   return stat;
 }
@@ -944,7 +944,7 @@ bool FixRattle::check3angle(double **v, int m, bool checkr, bool checkv)
   double db2 = fabs(sqrt(MathExtra::dot3(r02,r02))-bond2);
   double db12 = fabs(sqrt(MathExtra::dot3(r12,r12))-bond12);
 
-  stat = !(checkr && (db1 > tol || db2 > tol || db12 > tol));
+  stat = !checkr || (db1 <= tol && db2 <= tol && db12 <= tol);
 
   if (derr_max < db1/bond1)    derr_max = db1/bond1;
   if (derr_max < db2/bond2)    derr_max = db2/bond2;
@@ -962,7 +962,7 @@ bool FixRattle::check3angle(double **v, int m, bool checkr, bool checkv)
   if (verr_max < dv2)    verr_max = dv2;
   if (verr_max < dv12)   verr_max = dv12;
 
-  stat = !(checkv && (dv1 > tol || dv2 > tol || dv12> tol));
+  stat = !checkv || (dv1 <= tol && dv2 <= tol && dv12<= tol);
 
 #if RATTLE_RAISE_ERROR
   if (!stat) error->one(FLERR,"Velocity constraints are not satisfied up to desired tolerance!");
diff --git a/src/input.cpp b/src/input.cpp
index ef0433dc99..1dc2b00ebc 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -607,7 +607,7 @@ void Input::substitute(char *&str, char *&str2, int &max, int &max2, int flag)
         paren_count = 0;
         i = 0;
 
-        while (var[i] != '\0' && !(var[i] == ')' && paren_count == 0)) {
+        while (var[i] != '\0' && (var[i] != ')' || paren_count != 0)) {
           switch (var[i]) {
           case '(': paren_count++; break;
           case ')': paren_count--; break;