通过包裹层来确定最小能量形交叉点:在合集群理论中探索地面和激发状态交叉点
Sara Angelico1, Eirik F Kjønstad1, Henrik Koch1
1Department of Chemistry, Norwegian University of Science and Technology, NTNU, 7491 Trondheim, Norway.
The journal of physical chemistry letters
|January 8, 2025
概括
本研究介绍了一种算法,用于在不需要非adiabatic合向量的情况下找到最小能量的形交叉点. 这种方法避免了结合集群理论的计算问题,准确地描述了基本状态几何.
科学领域:
- 计算化学是一种计算化学.
- 理论化学是一种理论化学.
- 摄影化学的使用.
背景情况:
- 最小能量形交叉点 (MECI) 对于理解光化学反应至关重要.
- 定位MECI在计算上具有挑战性,通常需要非adiabatic合向量.
- 合集群 (CC) 理论可以在形交叉点面对数值文物.
研究的目的:
- 开发和评估一种用于定位MECI的算法,可以绕过非adiabatic合向量的需求.
- 解决和克服与形交叉点的CC理论相关的融合问题.
- 评估CC单双 (CCSD) 模型用于描述MECI几何形状的准确性.
主要方法:
- 一个算法,最大限度地减少了包裹交叉的超表面上的能量.
- 限制电子状态具有很小,非零的能量差异,以避免数值问题.
- 使用合集群单双 (CCSD) 模型进行几何优化.
主要成果:
- 该算法成功地定位MECI,而无需计算非adiabatic合向量.
- 限制能量差异可以防止CC理论中的数值工件和收问题.
- CCSD模型准确地描述了MECI的几何形状与各种系统的基本状态.
结论:
- 开发的算法提供了一个强大的方法来找到MECI.
- 结合集群理论,特别是CCSD,可以可靠地描述最小能量形交叉点的几何形状.
- 这种方法表明使用CC理论在非adiabatic动力学模拟中用于基态放松的潜力.
相关概念视频
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
956
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
956
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
1.0K
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
1.0K
02:30Stability of Substituted Cyclohexanes
12.3K
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
12.3K
01:27¹H NMR: Long-Range Coupling
1.7K
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
1.7K
01:12Reduced Mass Coordinates: Isolated Two-body Problem
1.2K
In classical mechanics, the two-body problem is one of the fundamental problems describing the motion of two interacting bodies under gravity or any other central force. When considering the motion of two bodies, one of the most important concepts is the reduced mass coordinates, a quantity that allows the two-body problem to be solved like a single-body problem. In these circumstances, it is assumed that a single body with reduced mass revolves around another body fixed in a position with an...
1.2K
03:35Hybridization of Atomic Orbitals II
31.8K
sp3d and sp3d 2 Hybridization
31.8K