="l00223"></a><span class="lineno">  223</span>&#160;            <span class="keyword">virtual</span> <span class="keywordtype">void</span> Interaction(<span class="keywordtype">size_t</span> index_i, Real dt = 0.0)<span class="keyword"> override</span></div><div class="line"><a name="l00224"></a><span class="lineno">  224</span>&#160;<span class="keyword">            </span>{</div><div class="line"><a name="l00225"></a><span class="lineno">  225</span>&#160;                Real Vol_i = Vol_[index_i];</div>