LaScO $_3$多体电子结构的实空间量子Monte Carlo研究
Many-body electronic structure of LaScO$_3$ by real space quantum Monte Carlo
摘要：
我们提出了真正的空间量子蒙特卡罗（QMC）计算scandate LaScO $_3$，被证明是具有挑战性的传统的电子结构的方法，由于强大的相关效应导致不准确的带隙从DFT和$GW$方法相比，与现有的实验数据。除了计算一个准确的QMC带隙校正超晶胞尺寸偏差，并与大量的实验一致，我们还预测的结合能的晶体使用标准的固定节点QMC没有任何经验或非变分参数。我们发现，促进（光学）间隙和基本间隙同意彼此说明一个明显的理想晶体中没有显着的激子效应。我们在采用不同基组的两个独立轨道上获得了完全一致的结果（平面波与局部高斯），不同的代码产生轨道（\textsc{Quantum Espresso}与\textsc{Crystal}），不同的QMC代码（\textsc{Qmcpack}与\textsc{Qwalk}）和不同的高精度伪电位（ccECP与Troullier-Martins）展示了QMC方法和工具在强相关问题研究中的成熟度和一致性。
英文摘要：
We present real space quantum Monte Carlo (QMC) calculations of the scandate LaScO$_3$ that proved to be challenging for traditional electronic structure approaches due to strong correlation effects resulting in inaccurate band gaps from DFT and $GW$ methods when compared with existing experimental data. Besides calculating an accurate QMC band gap corrected for supercell size biases and in agreement with numerous experiments, we also predict the cohesive energy of the crystal using the standard fixed-node QMC without any empirical or non-variational parameters. We show that promotion (optical) gap and fundamental gap agree with each other illustrating a clear absence of significant excitonic effects in the ideal crystal. We obtained these results in perfect consistency in two independent tracks that employ different basis sets (plane wave vs. localized gaussians), different codes for generating orbitals (\textsc{Quantum Espresso} vs. \textsc{Crystal}), different QMC codes (\textsc{Qmcpack} vs. \textsc{Qwalk}) and different high-accuracy pseudopotentials (ccECPs vs. Troullier-Martins) presenting the maturity and consistency of QMC methodology and tools for studies of strongly correlated problems.
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