We implement Epstein–Nesbet perturbative corrections in the third-order for the initiator approximation of the configuration space quantum Monte Carlo. An improved sampling algorithm is proposed to address the stochastic noise of the corrections. The stochastic error for the perturbative corrections is considerably larger than that for the reference energy, and it fails to provide reasonable results unless a very long imaginary time integration is performed. The new sampling algorithm accumulates rejected walkers from multiple independent steps to cover a larger portion of the secondary space. The performance of the perturbative corrections is demonstrated for small molecules.

中文翻译：

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对构型空间量子蒙特卡罗的引发剂逼近的三阶爱泼斯坦-内斯贝特微扰校正。

我们针对构型空间量子蒙特卡罗的引发剂逼近在三阶上实现爱泼斯坦-内斯贝特摄动校正。提出了一种改进的采样算法来解决校正的随机噪声。微扰校正的随机误差比参考能量的随机误差大得多，并且除非执行非常长的虚拟时间积分，否则它无法提供合理的结果。新的采样算法从多个独立步骤中累积了被拒绝的步行者，以覆盖更大的次空间。对于小分子，证明了微扰校正的性能。