EAGER: Correlator product states for quantum chemistry and quantum Monte Carlo

康奈尔大学的Garnet K.Chan和Cyrus Umrigar是由理论、模型和计算方法计划颁发的一项急切奖项资助的，他们探索一类新的电子波函数。这种波函数有可能创建一种新的量子化学框架，使电子结构的研究能够包含全球电子关联。新的方法涉及被称为关联积态(CPS)的状态组，这些状态组从根本上不同于已有的电子结构方法中使用的波函数，如组态相互作用、耦合团簇、双态等。对模型系统的初步研究表明，与其他类型的波函数相比，CPS能更准确、更有效地描述强关联量子问题。在这个探索性项目中，CPS方法被扩展到描述小分子和元素团簇的解离。新的波函数作为扩散量子蒙特卡罗研究的起点是非常有用的。目前，正在采取措施表明，CPS ansatz为理解整个类别的电子关联提供了框架，这些关联对过渡金属化学、激发态、键断裂和复杂材料至关重要。更广泛的影响是通过探索电子结构研究的变革性方法实现的，这些研究影响到使用量子化学和量子蒙特卡罗方法的化学家和材料科学家的广泛受众。

Garnet K. Chan and Cyrus Umrigar of Cornell University are funded by an EAGER award from the Theory, Models and Computational Methods program to explore a novel class of electronic wave functions. Such wave functions have the potential of creating a new quantum chemistry framework enabling studies of electronic structure with global inclusion of electron correlation. The new approach involves groups of states referred as Correlator Product States (CPS) that are fundamentally different from the wave functions used in established electronic structure approaches such as configuration interaction, coupled cluster, geminal, among others. Initial studies on model systems show that CPS can describe strongly correlated quantum problems more accurately and more efficiently than other classes of wave functions. In this exploratory project the CPS approach is extended to describe dissociation of small molecules and elemental clusters. The new wave functions are very useful as the starting point in diffusion quantum Monte Carlo studies. Currently steps are underway to show that the CPS ansatz provides the framework for understanding an entire class of electronic correlations that are central to transition metal chemistry, excited states, bond-breaking, and complex materials. Broader impacts are achieved by the transformative approach to explore electronic structure studies that affect a broad audience of chemists and material scientists using quantum chemistry and quantum Monte Carlo methodologies.