OSV-MP2波函数的三阶多体展开及其低阶标度分析梯度计算
Third-order many-body expansion of OSV-MP2 wavefunction for low-order scaling analytical gradient computation
摘要：
我们提出了一种多体展开（MBE）公式和实现，用于基于我们早期的工作（Zhou等人，J. Chem. Theory Comput. 2020，16，196-210）。OSV-MP2波函数的三阶MBE（3）展开采用了轨道特定的成簇和长程终止方案，避免了MBE能体的逐项微分。我们实现了更好的效率，利用算法的稀疏性，允许修剪出无关紧要的拟合积分和OSV松弛。利用这些近似，本实施方式在一系列分子上进行基准测试，这些分子分别在用于计算MBE（3）-OSV-MP2振幅和梯度方程的线性和二次方案中显示经济缩放，并且产生与原始OSV-MP2结果相当的正常精度。通过共享存储器单侧通信的基于MPI-3的并行性被进一步开发，以通过将MBE（3）轨道簇分类为分布在跨许多节点的多个进程上的独立任务来改善并行可扩展性和存储器可访问性，支持全局和局部数据位置，其中区分并相应地放置不同大小的所选MBE（3）-OSV-MP2中间体。我们的MBE（3）-OSV-MP2分析梯度实现的准确性和效率水平最终在两个应用中得到了说明：我们表明，当调节配体长度时，可以区分机械互锁的Cu-索烃络合物的细微配位结构差异;并且卟啉分子动力学揭示了由与氢转移相关的软化N-H伸缩引起的振动特征的出现，第一次使用MP2水平的电子相关和经典核。
英文摘要：
We present a many-body expansion (MBE) formulation and implementation for efficient computation of analytical energy gradients from OSV-MP2 theory based on our earlier work (Zhou et al. J. Chem. Theory Comput. 2020, 16, 196-210). The third-order MBE(3) expansion of OSV-MP2 wavefunction was developed to adopt the orbital-specific clustering and long-range termination schemes, which avoids term-by-term differentiations of the MBE energy bodies. We achieve better efficiency by exploiting the algorithmic sparsity that allows to prune out insignificant fitting integrals and OSV relaxations. With these approximations, the present implementation is benchmarked on a range of molecules that show an economic scaling in the linear and quadratic regimes for computing MBE(3)-OSV-MP2 amplitude and gradient equations, respectively, and yields normal accuracy comparable to the original OSV-MP2 results. The MPI-3-based parallelism through shared memory one-sided communication is further developed for improving parallel scalability and memory accessibility by sorting the MBE(3) orbital clusters into independent tasks that are distributed on multiple processes across many nodes, supporting both global and local data locations in which selected MBE(3)-OSV-MP2 intermediates of different sizes are distinguished and accordingly placed. The accuracy and efficiency level of our MBE(3)-OSV-MP2 analytical gradient implementation is finally illustrated in two applications: we show that the subtle coordination structure differences of mechanically interlocked Cu-catenane complexes can be distinguished when tuning ligand lengths; and the porphycene molecular dynamics reveals the emergence of the vibrational signature arising from softened N-H stretching associated with hydrogen transfer, using an MP2 level of electron correlation and classical nuclei for the first time.
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