Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
Department of Chemistry, University of California, Berkeley, California 94720, USA.
J Chem Phys. 2017 Oct 28;147(16):164114. doi: 10.1063/1.5008743.
In the regime where traditional approaches to electronic structure cannot afford to achieve accurate energy differences via exhaustive wave function flexibility, rigorous approaches to balancing different states' accuracies become desirable. As a direct measure of a wave function's accuracy, the energy variance offers one route to achieving such a balance. Here, we develop and test a variance matching approach for predicting excitation energies within the context of variational Monte Carlo and selective configuration interaction. In a series of tests on small but difficult molecules, we demonstrate that the approach is effective at delivering accurate excitation energies when the wave function is far from the exhaustive flexibility limit. Results in C, where we combine this approach with variational Monte Carlo orbital optimization, are especially encouraging.
在传统电子结构方法无法通过详尽的波函数灵活性来实现精确能量差异的情况下，需要采用严格的方法来平衡不同状态的精度。作为衡量波函数精度的直接指标，能量方差为实现这种平衡提供了一种途径。在这里，我们开发并测试了一种方差匹配方法，用于在变分蒙特卡罗和选择构型相互作用的背景下预测激发能。在对小分子但困难分子的一系列测试中，我们证明了当波函数远未达到详尽的灵活性极限时，该方法在提供准确的激发能方面是有效的。在 C 中，我们将这种方法与变分蒙特卡罗轨道优化相结合的结果尤其令人鼓舞。
