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首页> 外文期刊>The Journal of Chemical Physics >Communications: Survival of the fittest: Accelerating convergencein full configuration-interaction quantum Monte Carlo
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Communications: Survival of the fittest: Accelerating convergencein full configuration-interaction quantum Monte Carlo

机译：通信：优胜劣汰：加速全组态相互作用量子蒙特卡罗的收敛

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摘要

We provide a very simple adaptation of our recently published quantum Monte Carlo algorithm infull configuration-interaction (Slater determinant) spaces which dramatically reduces the number ofwalkers required to achieve convergence. A survival criterion is imposed for newly spawnedwalkers. We define a set of initiator determinants such that progeny of walkers spawned from suchdeterminants onto unoccupied determinants are able to survive, while the progeny of walkers not inthis set can survive only if they are spawned onto determinants which are already occupied. The setof initiators is originally defined to be all determinants constructable from a subset of orbitals, inanalogy with complete-active spaces. This set is dynamically updated so that if a noninitiatordeterminant reaches an occupation larger than a preset limit, it becomes an initiator. The newalgorithm allows sign-coherent sampling of the FCI space to be achieved with relatively fewwalkers. Using the N_2molecule as an illustration, we show that rather small initiator spaces andnumbers of walkers can converge with submilliHartree accuracy to the known fullconfiguration-interaction (FCI) energy (in the cc-pVDZ basis), in both the equilibrium geometry andthe multiconfigurational stretched case. We use the same method to compute the energy withcc-pVTZ and cc-pVQZ basis sets, the latter having an FCI space of over 10~(15)with very modestcomputational resources.
机译：我们对最近发布的量子蒙特卡洛算法在完全配置相互作用（Slater行列式）空间中进行了非常简单的修改，这极大地减少了实现收敛所需的行人数量。对新产卵的步行者施加生存标准。我们定义了一组启动子决定因素，以使从此类决定因素产生的步行者的后代能够生存，而不在此集合中的步行者的后代只有在已经被占领的决定因素产生时才能生存。初始发起者的集合最初定义为可以从轨道的子集构造的所有行列式，与完全活动空间无关。动态更新此集合，以便如果非启动子决定因素达到的职业大于预设限制，它将成为启动器。新算法允许相对较少的行进者实现FCI空间的符号相干采样。以N_2分子为例，我们表明，在平衡几何和多构型拉伸情况下，相当小的引发剂空间和数量的步行者都可以以submilliHartree精度收敛到已知的全构图相互作用（FCI）能量（以cc-pVDZ为基础） 。我们使用相同的方法来计算cc-pVTZ和cc-pVQZ基集的能量，后者的FCI空间超过10〜（15），且计算资源非常适中。

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