相关实验视频

Updated: Jun 17, 2025

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Published on: May 27, 2020

一种有吸引力的方法来纠正失踪的单身刺激在单元配对集群双重理论中的吸引力

Zachary W Windom^1,2, Daniel Claudino², Rodney J Bartlett¹

¹Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States.

The journal of physical chemistry. A

|August 8, 2024

概括

仅使用双刺激 (UCCD) 的结合集群方法可以通过添加缺失单刺激的纠正来改进. 新的方法 (UCCD[4S]和UCCD[6S]) 取得了与更复杂的方法可比的结果.

科学领域:

量子化学是一个量子化学.
计算化学计算化学
理论化学理论化学

背景情况:

合集群 (CC) 方法对于准确描述电子相关性至关重要.
结合集群双重 (CCD) 方法,仅专注于双重激发,提供了一个计算效率高的方法.
然而,忽视CCD中的单一激发会导致显著的不准确性.

研究的目的:

为了研究在单元合集群双重 (UCCD) 方法中缺失的单一激发效应的恢复.
通过对单个刺激进行低级多体扰动理论 (MBPT) 校正来开发新的UCCD变体.
评估这些新方法的性能,与已建立的合集群方法相比.

主要方法:

有限顺序的单元合集群 (UCC) 能量函数的导出.
基于MBPT的错过单次激发的扰动性估计的定义.
开发UCCD[4S]和UCCD[6S]方法,分别包含第四级和第六级MBPT校正.
适用于标准和受电子对限制的UCCD形式.

主要成果:

在UCCD[4S]和UCCD[6S]方法有效地恢复缺失单一激发的影响.
增加这些后期扰动性纠正的UCCD产生了与更严格的合集群单双 (CCSD) 方法相提并论的结果.
电子对受限制的替代品在相同的方法上只显示了边际的改进.

结论:

为单个激发进行低级MBPT校正是提高UCCD方法准确性的可行策略.
开发的UCCD[4S]和UCCD[6S]方法提供了一个计算效率高的路线,接近CCSD准确度.
这些发现为改善量子化学计算的成本性能比提供了一个有希望的途径.

更多相关视频

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Published on: April 8, 2020

Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid

Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid

Published on: January 25, 2020

相关概念视频

Hybridization of Atomic Orbitals II

Hybridization of Atomic Orbitals II

sp3d and sp3d 2 Hybridization

Molecular Orbital Theory II

Molecular Orbital Theory II

Molecular Orbital Energy Diagrams

Hybridization of Atomic Orbitals I

Hybridization of Atomic Orbitals I

The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...

¹H NMR: Interpreting Distorted and Overlapping Signals

¹H NMR: Interpreting Distorted and Overlapping Signals

Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...

Molecular Orbital Theory I

Molecular Orbital Theory I

Overview of Molecular Orbital Theory

Spin–Spin Coupling: One-Bond Coupling

Spin–Spin Coupling: One-Bond Coupling

Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...