Decoherence corrections increase the accuracy of mixed quantum–classical nonadiabatic molecular dynamics methods, but they typically require explicit knowledge of the potential energy surfaces of all occupied electronic states. This requirement renders them impractical for applications in which large numbers of electronic states are occupied. The authors recently introduced the collapse to a block (TAB) decoherence correction [M. P. Esch and B. G. Levine, J. Chem. Phys. 152, 234105 (2020)], which incorporates a state-pairwise definition of decoherence time to accurately describe dynamics on more than two electronic states. In this work, TAB is extended by introduction of a scheme for efficiently computing a small number of approximate eigenstates of the electronic Hamiltonian, eliminating the need for explicit knowledge of a large number of potential energy surfaces. This adaptation of TAB for dense manifolds of states (TAB-DMS) is systematically improvable by increasing the number of computed approximate eigenstates. Application to a series of one-dimensional model problems demonstrates that TAB-DMS can be accurate when even a very modest number of approximate eigenstates are computed (four in all models tested here). Comparison of TAB simulations to exact quantum dynamical simulations indicates that TAB is quite accurate so long as the decoherence correction is carefully parameterized.

中文翻译：

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经退相干校正的埃伦菲斯特分子动力学在许多电子态上的表现。

退相干校正提高了混合量子-经典非绝热分子动力学方法的准确性，但是它们通常需要对所有占据的电子态的势能面有明确的了解。该要求使它们对于占用大量电子状态的应用不切实际。作者最近将塌陷引入了一个区块（TAB）退相干校正[MP Esch and BG Levine，J. Chem。物理 152，234234（2020）]，其中包含了相干时间的状态对定义，以准确描述两个以上电子状态的动力学。在这项工作中，通过引入一种可有效计算电子哈密顿量的少量近似本征态的方案来扩展TAB，从而无需显着了解大量势能面。通过增加计算的近似本征态的数量，系统上可以改善TAB对密集状态流形（TAB-DMS）的适应。在一系列一维模型问题上的应用表明，即使只计算了非常少量的近似本征态，TAB-DMS仍是准确的（此处测试的所有模型中有四个）。