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<p>Hello community!</p>
<p>i hope someone can help me understand some code changes in the do_update_md() function in update.cpp.</p>
<p>In the case where it advances r and v in the leap-frog scheme together with the berendsen thermostat<br>
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<p>(last two else if { } and else { }) in version 4.0.7. it looks like this</p>
<p><span>vv = lg*(vn + f[n][d]*w_dt);<br>
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<p><span>where lg is the lambda-scaling factor from the thermostat and w_dt is dt/m.</span></p>
<p><span>Instead in version 4.5. and higher:</span></p>
<p><span></span><span> vv = lg*vn + f[n][d]*w_dt;</span></p>
<p><span><br>
</span></p>
<p><span>The original paper (<span>The Journal of Chemical Physics 81, 3684 (1984); doi: 10.1063/1.448118</span>) seems to scale</span></p>
<p><span>both old velocity and force. Btw in <span>do_update_visc</span>() scaling is done to both.</span></p>
<p><span>What is the purpose of this?</span></p>
<p><span>any help is much appreciated,</span></p>
<p><span>regards Martin<br>
</span></p>
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