Cluster Amplitudes and Their Interplay with Self‐Consistency in Density Functional Methods
Cluster Amplitudes and Their Interplay with Self‐Consistency in Density Functional Methods
复制标题
密度泛函方法中的簇振幅及其与自一致性的相互作用
DOI：
10.1002/cphc.202200592
复制
发表时间：
2023
期刊：
影响因子：
2.9
通讯作者：
Mosquera, Martín A.
中科院分区：
文献类型：
--
作者：
Jacobson, Greta;Marmolejo‐Tejada, Juan M.;Mosquera, Martín A.
密度泛函理论（DFT）为分子体系和材料的研究提供了方便的电子结构方法。常规的Kohn-Sham DFT计算依赖于幺正变换来确定基态电子密度、基态能量和相关性质。然而，对于分子系统解离成开壳层碎片，由于大量密度泛函近似中存在的自相互作用误差，基于这种类型的变换的自洽过程产生了众所周知的电荷离域问题。为了避免这个问题，我们之前证明了耦合团簇理论的团簇算子可以在DFT的上下文中使用，以替代和近似的方式解决基态自洽问题。本文进一步研究了单团簇算符在分子基态计算中的应用。两个近似推导和探讨：i）一个线性化的计划，用于确定集群振幅的二次方程。 ii）以非自洽场方式进行计算的效果。 这些方法被发现能够提高系统的能量和密度，并且在任何一种情况下都是相当稳定的。在这项工作中讨论的理论框架可以用来描述，具有额外的灵活性，量子系统，显示具有挑战性的功能，并需要扩展的理论方法。
Density functional theory (DFT) provides convenient electronic structure methods for the study of molecular systems and materials. Regular Kohn‐Sham DFT calculations rely on unitary transformations to determine the ground‐state electronic density, ground state energy, and related properties. However, for dissociation of molecular systems into open‐shell fragments, due to the self‐interaction error present in a large number of density functional approximations, the self‐consistent procedure based on the this type of transformation gives rise to the well‐known charge delocalization problem. To avoid this issue, we showed previously that the cluster operator of coupled‐cluster theory can be utilized within the context of DFT to solve in an alternative and approximate fashion the ground‐state self‐consistent problem. This work further examines the application of the singles cluster operator to molecular ground state calculations. Two approximations are derived and explored: i) A linearized scheme of the quadratic equation used to determine the cluster amplitudes. ii) The effect of carrying the calculations in a non‐self‐consistent field fashion. These approaches are found to be capable of improving the energy and density of the system and are quite stable in either case. The theoretical framework discussed in this work could be used to describe, with an added flexibility, quantum systems that display challenging features and require expanded theoretical methods.