I'm a fucking idiot

The limit I set to avoid divisions by zero was wront and collisions were
being skipped. It is corrected now.

src/modules/init/moduleInput.f90

@@ -155,7 +155,7 @@ MODULE moduleInput
           sigmaVrel_ref = PI*(r_ref+r_ref)**2*v_ref !reference cross section times velocity
 
         ELSE
-          sigmaVrel_ref = 0.D0 !Assume no collisions
+          sigmaVrel_ref = L_ref**2 * v_ref
 
         END IF
 

src/modules/mesh/moduleMesh.f90

@@ -1016,7 +1016,7 @@ MODULE moduleMesh
 
             W = partTemp%part%v - velocity
             normW = NORM2(W)
-            IF (normW > 1.D-10) THEN
+            IF (normW < 1.D-12) THEN
               !If relative velocity is too low, skip collision and move to next particle
               partTemp => partTemp%next
 
@@ -1055,6 +1055,7 @@ MODULE moduleMesh
             deltaV =  dW(1)*e1 + dW(2)*(COS(rnd)*e2 + SIN(rnd)*e3)
 
             totalDeltaV_ij = totalDeltaV_ij + NORM2(deltaV)
+
             !Change particle velocity
             partTemp%part%v = partTemp%part%v + deltaV
                                                
@@ -1078,6 +1079,7 @@ MODULE moduleMesh
             normDeltaV = totalDeltaV_ij / REAL(cell%listPart_in(j)%amount) *       &
                          (coulombMatrix(k)%sp_i%weight*coulombMatrix(k)%sp_i%m) /  &
                          (coulombMatrix(k)%sp_j%weight*coulombMatrix(k)%sp_j%m)
+
             !Loop over particles of species_j
             partTemp => cell%listPart_in(j)%head
             DO WHILE(ASSOCIATED(partTemp))
@@ -1090,7 +1092,7 @@ MODULE moduleMesh
   
               W = partTemp%part%v - velocity
               normW = NORM2(W)
-              IF (normW > 1.D-10) THEN
+              IF (normW < 1.D-12) THEN
                 !If relative velocity is too low, skip collision and move to next particle
                 partTemp => partTemp%next
 
@@ -1111,7 +1113,7 @@ MODULE moduleMesh
               dW(2) =                ABS(randomMaxwellian()*SQRT(delta_per_square*tauMin))
 
               !Normalize with average exchange per particle
-              !TODO: This is a dirty trick, it should not be neccessary but I don't lnow why it is.
+              !TODO: This is a dirty trick to ensure conservation between species
               dW = normDeltaV*dW/NORM2(dW)
 
               !System of reference for the velocity change