金刚石结构硅的凝聚和激发的量子蒙特卡罗研究：基准和系统偏差的控制
Cohesion and excitations of diamond-structure silicon by quantum Monte Carlo: Benchmarks and control of systematic biases
摘要：
我们进行了量子蒙特卡罗（QMC）计算的硅晶体的精度和系统的偏差，影响电子结构特性的重点。结果表明，64和216个原子的超胞提供了一个很好的一致性外推的能量每原子的热力学极限的基态，激发态和电离态。我们计算了基态凝聚能与$\textit{systematic and statistical errors}$低于$\approx$ 0.05 eV。基态表现出一个固定的节点误差只有$1.3(2)\%$的相关能量，这表明一个异常高的精度相应的单参考试验波函数。我们得到了一个很好的协议之间的光学和准粒子的差距，肯定了激子效应的边际影响。我们最精确的带隙结果与实验相差约0.2 eV。这种差异被分配到一个组合的残余有限大小和固定节点的错误。我们已经估计了晶体费米能级参考真空，使我们能够计算与实验一致的价带和导带的边缘。
英文摘要：
We have carried out quantum Monte Carlo (QMC) calculations of silicon crystal focusing on the accuracy and systematic biases that affect the electronic structure characteristics. The results show that 64 and 216 atom supercells provide an excellent consistency for extrapolated energies per atom in the thermodynamic limit for ground, excited, and ionized states. We have calculated the ground state cohesion energy with both $\textit{systematic and statistical errors}$ below $\approx$0.05 eV. The ground state exhibits a fixed-node error of only $1.3(2)\%$ of the correlation energy, suggesting an unusually high accuracy of the corresponding single-reference trial wave function. We obtain a very good agreement between optical and quasiparticle gaps that affirms the marginal impact of excitonic effects. Our most accurate results for band gaps differ from the experiments by about 0.2 eV. This difference is assigned to a combination of residual finite-size and fixed-node errors. We have estimated the crystal Fermi level referenced to vacuum that enabled us to calculate the edges of valence and conduction bands in agreement with experiments.
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