全组态相互作用量子Monte Carlo中的预处理和微扰估计
Preconditioning and perturbative estimators in full configuration interaction quantum Monte Carlo
摘要：
我们建议使用预处理FCIQMC，结合扰动估计，大大提高了算法的效率。预处理的使用允许使用接近统一的时间步长（没有时间步长错误），前提是每个步行者进行多次产卵尝试。我们表明，这种方法大大减少了统计噪声的扰动修正发起人的错误，提高了准确性的FCIQMC，但可以遭受显着的噪声在原来的计划。因此，使用预处理和扰动校正估计相结合，导致一个显着更有效的算法。此外，一个更简单的方法来采样FCIQMC变分和扰动估计，它也允许计算的能量方差。这些发展进行了研究，并适用于苯（30 e，108 o），一个例子，准确的治疗是不可能与原来的方法。
英文摘要：
We propose the use of preconditioning in FCIQMC which, in combination with perturbative estimators, greatly increases the efficiency of the algorithm. The use of preconditioning allows a time step close to unity to be used (without time-step errors), provided that multiple spawning attempts are made per walker. We show that this approach substantially reduces statistical noise on perturbative corrections to initiator error, which improve the accuracy of FCIQMC but which can suffer from significant noise in the original scheme. Therefore, the use of preconditioning and perturbatively-corrected estimators in combination leads to a significantly more efficient algorithm. In addition, a simpler approach to sampling variational and perturbative estimators in FCIQMC is presented, which also allows the variance of the energy to be calculated. These developments are investigated and applied to benzene (30e,108o), an example where accurate treatment is not possible with the original method.
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