etRelPos(p1,w);
                        
                        % Check if separation is greater than cutoff distance
                        % Assumption: cutoff ratio applies to particle radius
                        if (int.kinemat.separ >= this.cutoff * p1.radius)
                            % Remove interaction references from particle
                            % (neigh_w is cleaned by searching the id
                            %  to avoid error when it is heterogeneous:
                         