振动循环二元体谱的模拟使用第二阶米勒-普莱塞特扰动理论和配置交互倍数
Brendan M Shumberger1, T Daniel Crawford1
1Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.
Journal of chemical theory and computation
|August 13, 2024
概括
本研究引入了使用包括电子相关性在内的先进方法对原子轴张量 (AAT) 的新计算. 这些方法显著影响振动循环二元化 (VCD) 频谱,特别是对于奇拉分子.
科学领域:
- 计算化学计算化学
- 量子化学 是一个量子化学.
- 频谱学是一种光谱学.
背景情况:
- 原子轴张量 (AAT) 对于理解分子性质至关重要.
- 以前的计算往往忽略了动态电子相关性效应.
- 准确的AAT对于解释振动圆二极化 (VCD) 频谱至关重要.
研究的目的:
- 执行AAT的第一个单一参考计算,其中包括动态电子相关性.
- 研究电子相关性对AAT和VCD光谱的影响.
- 评估Møller-Plesset扰动理论 (MP2) 和配置交互双重 (CID) 方法的性能.
主要方法:
- 采用基于波函数的方法,特别是二次Møller-Plesset扰动理论 (MP2) 和配置交互倍数 (CID).
- 计算了与核坐标和磁场相关的相关波函数的数值导数的重叠.
- 在小分子上测试了这些方法:H2二聚合物, (P) 过氧化和H2O.
主要成果:
- 通过MP2和CID计算的AAT与Hartree-Fock (HF) 相比,在不同基础集中观察到显著的偏差 (高达49%).
- 对于 (P) - 过氧化 (偏差高达62%) 的振动圆形二元化 (VCD) 旋转强度,证明了实质性的电子相关性效应.
- 突出了动态电子相关性对由此产生的旋转强度和VCD光谱的显著影响.
结论:
- 动态电子相关性显著影响AAT计算和VCD光谱.
- MP2和CID方法提供比HF更准确的AAT和VCD光谱.
- 这些发现对于准确的分子性质预测和光谱解释至关重要.
更多相关视频
相关概念视频
¹H NMR: Interpreting Distorted and Overlapping Signals
1.0K
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...
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...
1.0K
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
1.3K
A covalently bonded heteronuclear diatomic molecule can be modeled as two vibrating masses connected by a spring. The vibrational frequency of the bond can be expressed using an equation derived from Hooke's law, which describes how the force applied to stretch or compress a spring is proportional to the displacement of the spring. In this case, the atoms behave like masses, and the bond acts like a spring.
According to Hooke's law, the vibrational frequency is directly proportional to...
According to Hooke's law, the vibrational frequency is directly proportional to...
1.3K
UV–Vis Spectroscopy: Molecular Electronic Transitions
1.4K
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this...
1.4K
IR Spectroscopy: Molecular Vibration Overview
2.0K
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental vibrational motions that result in infrared absorption can be classified as stretching or bending vibrations.
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
2.0K
Molecular Spectroscopy: Absorption and Emission
2.0K
Molecules possess discrete energy levels called quantum states. Unlike atoms, which have simpler energy levels, molecules possess additional rotational and vibrational energy levels. Each energy level is separated by an energy gap, with the gaps between adjacent electronic, vibrational, and rotational levels varying significantly. The three types of energy levels in a diatomic molecule are shown in Figure 1.
2.0K
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
1.0K
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
1.0K


