论文标题
朝着固体扩散蒙特卡洛的固定节点近似的系统改进 - 钻石的案例研究
Towards a Systematic Improvement of the Fixed-Node Approximation in Diffusion Monte Carlo for Solids -- A Case Study In Diamond
论文作者
论文摘要
虽然扩散的蒙特卡洛（DMC）原则上是\ textit {ab intio}电子结构计算的确切随机方法，但实际上，必须使用固定节点近似和试验波形使用近似节点（或零）。这种近似引入了可能测试并系统地改进的能量的变异误差。在这里，我们提出了一种计算方法，该方法可产生试验波函数，并具有系统地改进的节点，用于DMC计算周期性固体。这些试验波函数是使用迭代性（CIPSI）方法进行扰动选择有效生成的。一个简单的协议，其中使用有限超级细胞的精确结果和近似结果来推断到热力学极限。
While Diffusion Monte Carlo (DMC) is in principle an exact stochastic method for \textit{ab initio} electronic structure calculations, in practice the fermionic sign problem necessitates the use of the fixed-node approximation and trial wavefunctions with approximate nodes (or zeros) must be used. This approximation introduces a variational error in the energy that potentially can be tested and systematically improved. Here, we present a computational method that produces trial wavefunctions with systematically improvable nodes for DMC calculations of periodic solids. These trial wavefunctions are efficiently generated with the configuration interaction using a perturbative selection made iteratively (CIPSI) method. A simple protocol in which both exact and approximate results for finite supercells are used to extrapolate to the thermodynamic limit is introduced.
