Piris Mario
Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), P.K. 1072, 20080 Donostia, Spain Donostia International Physics Center (DIPC), 20018 Donostia, Spain and IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.
Phys Rev Lett. 2021 Dec 3;127(23):233001. doi: 10.1103/PhysRevLett.127.233001.
The current work presents a natural orbital functional (NOF) for electronic systems with any spin value independent of the external potential being considered, that is, a global NOF (GNOF). It is based on a new two-index reconstruction of the two-particle reduced density matrix for spin multiplets. The emergent functional describes the complete intrapair electron correlation, and the correlation between orbitals that make up both the pairs and the individual electrons. The interorbital correlation is composed of static and dynamic terms. The concept of dynamic part of the occupation numbers is introduced. To evaluate the accuracy achieved with the GNOF, calculation of a variety of properties is presented. They include the total energies and energy differences between the ground state and the lowest-lying excited state with different spin of atoms from H to Ne, ionization potentials of the first-row transition-metal atoms (Sc-Zn), and the total energies of a selected set of 55 molecular systems in different spin states. The GNOF is also applied to the homolytic dissociation of selected diatomic molecules in different spin states and to the rotation barrier of ethylene, both paradigmatic cases of systems with significant multiconfigurational character. The values obtained agree with those reported at high level of theory and experimental data.
当前工作提出了一种适用于具有任意自旋值的电子系统的自然轨道泛函（NOF），该自旋值与所考虑的外部势无关，即一种全局NOF（GNOF）。它基于对自旋多重态的两粒子约化密度矩阵的一种新的双指标重构。所产生的泛函描述了完整的对内电子关联以及构成对和单个电子的轨道之间的关联。轨道间关联由静态项和动态项组成。引入了占据数动态部分的概念。为了评估GNOF所达到的精度，给出了各种性质的计算。这些性质包括从H到Ne的不同自旋原子的基态与最低激发态之间的总能量和能量差、第一行过渡金属原子（Sc - Zn）的电离势，以及一组55个处于不同自旋态的分子体系的总能量。GNOF还被应用于不同自旋态下选定双原子分子的均裂解离以及乙烯的旋转势垒，这两个都是具有显著多组态特征的体系的典型例子。所获得的值与在高水平理论和实验数据中报道的值一致。
