s.verlet_freq = 10 * this.freq;
                <span class="keyword">else</span>
                    this.verlet_freq = (this.verlet_dist - this.cutoff * rmax) / (2 * vmax * drv.time_step);
                <span class="keyword">end</span>
            <span class="keyword">end</span>
        <span class="keyword">end</span>

        <span class="comment">%------------------------------------------------------------------</span>
        <span class="keyword">function</span> execute(this,drv)
            <spa