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    <title>MLIP Dynamics</title>
    <meta name="description" content="Molecular dynamics (NVE) and diffusion Monte Carlo with machine-learning interatomic potentials, in your browser." />
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    <header>
      <a class="brand" href="./" title="Back to the network visualiser">MLIP<span>viz</span></a>
      <nav id="modes" title="What to run">
        <button data-mode="md" class="on" title="Classical molecular dynamics at constant energy">NVE dynamics</button>
        <button data-mode="dmc" title="Diffusion Monte Carlo: the quantum vibrational ground state">Diffusion Monte Carlo</button>
      </nav>
      <label title="The kind of model">Model <select id="kind"></select></label>
      <label title="Which trained weights">Weights <select id="model"></select></label>
      <label>Structure <select id="structure"></select></label>
      <label class="file">Open .xyz…<input id="xyz-file" type="file" accept=".xyz,.extxyz" /></label>
      <label class="md-only" id="force-mode-wrap" title="How forces are computed">Forces <select id="force-mode">
        <option value="conservative">conservative (−∂E/∂r)</option>
        <option value="direct">direct (non-conservative)</option></select></label>
      <label class="md-only" title="Initial temperature: Maxwell–Boltzmann velocities, no net momentum">T₀ <input id="temperature" type="number" value="300" min="0" max="5000" step="50" /> K</label>
      <label class="md-only" title="Time step (applies immediately)">Δt <input id="dt" type="number" value="0.5" min="0.05" max="5" step="0.05" /> fs</label>
      <label class="dmc-only" title="Target number of walkers (all are evaluated in batched passes)">Walkers <input id="walkers" type="number" value="500" min="20" max="20000" step="100" /></label>
      <label class="dmc-only" title="Imaginary time step, atomic units (applies immediately)">Δτ <input id="dtau" type="number" value="10" min="0.5" max="50" step="1" /> a.u.</label>
      <button id="run" class="on" title="Run or pause (Space)">Pause</button>
      <button id="restart" title="Start again from the starting structure (R)">Restart</button>
      <button id="theme" title="Theme"></button>
      <div id="status">starting…</div>
    </header>
    <main>
      <section id="stage">
        <div id="traj"></div>
        <div id="clock"></div>
        <div id="md-loading" hidden>
          <div class="loader-title"></div>
          <div class="loader-stage"></div>
          <div class="loader-bar"><i></i></div>
        </div>
      </section>
      <aside id="panel">
        <div class="tiles md-only">
          <div class="tile"><small>Temperature</small><b id="t-now">–</b><span id="t-mean"></span></div>
          <div class="tile"><small>Energy drift</small><b id="drift">–</b><span id="drift-max"></span></div>
          <div class="tile" title="Simulated nanoseconds per day of wall-clock time at this rate"><small>Speed</small><b id="speed">–</b><span id="ms"></span></div>
          <div class="tile flops-tile"><small>Compute</small><b id="flops">–</b><span id="flops-detail"></span></div>
        </div>
        <div class="tiles dmc-only">
          <div class="tile" title="Mean of E_ref − V_min over the second half of the run, with a blocking error"><small>Zero-point energy</small><b id="zpe">–</b><span id="zpe-detail"></span></div>
          <div class="tile"><small>Walkers</small><b id="walkers-now">–</b><span id="walkers-detail"></span></div>
          <div class="tile" title="Walker energies evaluated per day of wall-clock time at this rate"><small>Throughput</small><b id="samples">–</b><span id="samples-detail"></span></div>
          <div class="tile flops-tile"><small>Compute</small><b id="dmc-flops">–</b><span id="dmc-flops-detail"></span></div>
        </div>
        <figure class="md-only">
          <figcaption>Energy, eV, relative to the total at t = 0</figcaption>
          <div id="energy-chart"></div>
        </figure>
        <figure class="md-only">
          <figcaption>Temperature, K</figcaption>
          <div id="temp-chart"></div>
        </figure>
        <figure class="dmc-only">
          <figcaption>Reference energy E_ref − V_min, cm⁻¹</figcaption>
          <div id="eref-chart"></div>
        </figure>
        <figure class="dmc-only">
          <figcaption>Walkers</figcaption>
          <div id="pop-chart"></div>
        </figure>
        <p class="note md-only">
          Velocity Verlet at constant N, V and E. When the forces are the gradient of the energy and Δt is small
          enough, the total energy stays flat while kinetic and potential energy swap. From a relaxed start about
          half the initial kinetic energy goes into the potential, so the temperature settles near T₀/2. Direct
          forces are not a gradient, so the total energy drifts with them, and so it does with too large a Δt.
        </p>
        <p class="note dmc-only">
          Diffusion Monte Carlo for the nuclei. The structure is relaxed on the model's surface, then each walker,
          a copy of the molecule, takes Gaussian steps of variance ħ²Δτ/m and is copied or removed with weight
          exp(−Δτ (V − E<sub>ref</sub>)). E<sub>ref</sub> is adjusted to keep the number of walkers near the
          target, and its average above the minimum is the zero-point energy. The cloud shows the walkers aligned
          on the minimum; hydrogens spread the most. Walkers far below the minimum are in a hole in the model's
          surface and are removed.
        </p>
        <p class="note" id="flops-note">
          FLOPs are counted from the shapes of the kernels the model runs, with a multiply-add as 2. The rate is
          over the whole step, so it also covers the neighbour list, data transfers and reading back the results.
        </p>
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