Berger J Arjan, Loos Pierre-François, Romaniello Pina
Laboratoire de Chimie et Physique Quantiques, Université de Toulouse, CNRS, UPS, and European Theoretical Spectroscopy Facility (ETSF), Toulouse 31062, France.
Laboratoire de Chimie et Physique Quantiques, Université de Toulouse, CNRS, UPS, Toulouse 31062, France.
J Chem Theory Comput. 2021 Jan 12;17(1):191-200. doi: 10.1021/acs.jctc.0c00896. Epub 2020 Dec 11.
In this work, we show the advantages of using the Coulomb hole plus screened exchange (COHSEX) approach in the calculation of potential energy surfaces (PES). In particular, we demonstrate that, unlike perturbative and partial self-consistent approaches, such as eigenvalue self-consistent and quasi-particle (QP) self-consistent , the COHSEX approach yields smooth PES without irregularities and discontinuities. Moreover, we show that the ground-state PES obtained from the Bethe-Salpeter equation (BSE), within the adiabatic connection fluctuation dissipation theorem, built with QP energies obtained from perturbative COHSEX on top of Hartree-Fock (BSE@COHSEX@HF) yield very accurate results for diatomic molecules close to their equilibrium distance. When self-consistent COHSEX QP energies and orbitals are used to build the BSE equation, the results become independent of the starting point. We show that self-consistency worsens the total energies but improves the equilibrium distances with respect to BSE@COHSEX@HF. This is mainly due to the changes in the screening inside the BSE.
在这项工作中，我们展示了在势能面（PES）计算中使用库仑空穴加屏蔽交换（COHSEX）方法的优势。特别是，我们证明，与微扰和部分自洽方法不同，如本征值自洽和准粒子（QP）自洽方法，COHSEX方法能产生平滑的PES，没有不规则性和不连续性。此外，我们表明，在绝热连接涨落耗散定理框架下，由基于哈特里 - 福克（Hartree - Fock）之上的微扰COHSEX得到的QP能量构建的贝塞 - 萨尔皮特方程（BSE）所得到的基态PES，对于接近其平衡距离的双原子分子能给出非常准确的结果。当使用自洽的COHSEX QP能量和轨道来构建BSE方程时，结果变得与起始点无关。我们表明，相对于BSE@COHSEX@HF，自洽会使总能量变差，但会改善平衡距离。这主要是由于BSE内部屏蔽的变化。
