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首页> 外文期刊>The Journal of Chemical Physics >Energy window stochastic density functional theory
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Energy window stochastic density functional theory

机译：能源窗随机密度函数理论

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Linear scaling density functional theory is important for understanding electronic structure properties of nanometer scale systems. Recently developed stochastic density functional theory can achieve linear or even sublinear scaling for various electronic properties without relying on the sparsity of the density matrix. The basic idea relies on projecting stochastic orbitals onto the occupied space by expanding the Fermi-Dirac operator and repeating this for N-chi stochastic orbitals. Often, a large number of stochastic orbitals are required to reduce the statistical fluctuations (which scale as N chi-1/2) below a tolerable threshold. In this work, we introduce a new stochastic density functional theory that can efficiently reduce the statistical fluctuations for certain observable and can also be integrated with an embedded fragmentation scheme. The approach is based on dividing the occupied space into energy windows and projecting the stochastic orbitals with a single expansion onto all windows simultaneously. This allows for a significant reduction of the noise as illustrated for bulk silicon with a large supercell. We also provide theoretical analysis to rationalize why the noise can be reduced only for a certain class of ground state properties, such as the forces and electron density.
机译：线性缩放密度功能理论对于了解纳米级系统的电子结构性能很重要。最近开发的随机密度功能理论可以实现各种电子特性的线性甚至是索布林缩放，而不依赖于密度矩阵的稀疏性。基本思想依赖于通过扩展FERMI-DIRAC操作者将随机轨道投射到占用空间上，并对N-Chi随机轨道重复这一点。通常，需要大量随机轨道来减少低于可容许阈值的统计波动（以n chi-1/2）。在这项工作中，我们引入了一种新的随机密度泛函理论，可以有效地降低某些可观察到的统计波动，也可以与嵌入的碎片方案集成。该方法是基于将占用空间划分为能量窗口，并将随机轨道投射到同时的所有窗口上的单一扩展。这允许显着降低噪声，如图所示用大型超级电池的散装硅所示。我们还提供理论分析，以合理化为什么只能为某种地面状态属性减少噪声，例如力和电子密度。

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