相关实验视频
Updated: Jul 16, 2026

08:53
Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures
Published on: October 9, 2012
有限状态潜在能量表面构造:ab initio零点能量和振动平均旋转常数
1Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543. chmbrpa@nus.edu.sg
Journal of the American Chemical Society
|January 9, 2003
概括
这项研究结合了柯林斯·柯林斯的研究.
科学领域:
- 计算化学计算化学
- 量子力学就是量子力学.
- 物理化学 物理化学
背景情况:
- 准确的潜在能量表面 (PES) 对于理解分子行为至关重要.
- 构建 PES 的传统方法可能在计算上昂贵且范围有限.
- 柯林斯的插值方法提供了一个有前途的方法,可以从量子化学计算中生成准确的PES.
研究的目的:
- 首次将柯林斯的插值方法应用于有限状态问题.
- 将这种方法与量子扩散蒙特卡洛 (QDMC) 计算相结合.
- 为了准确地确定基态零点能量,振动平均旋转常数和甲的内部坐标.
主要方法:
- 采用了柯林斯的插值方法来构建PES.
- 采用量子扩散蒙特卡洛 (QDMC) 用于绑定状态计算.
- 使用复合方法进行计算,以近似QCISD (T)/6-311++G (df,2p) 理论水平.
主要成果:
- 实现了一种完全自动化的,从头开始的方法,包括所有九个核自由度.
- 该方法不需要关于 PES 功能形式的假设,并且具有完全的系统对称性.
- 计算的零点能量同意在最佳估计值的0.2%之内;旋转常数A0和B0分别在实验值的0.9%和0.3%之内.
结论:
- 结合的柯林斯插值和QDMC方法为束状态问题提供了准确和可概括的方法.
- 这种新的组合克服了以前方法的局限性,提供了无参数,对称性适应的PES构建.
- 该方法广泛适用于可接受量子化学计算和柯林斯插值技术的系统.
相关概念视频
Free Energy Changes for Nonstandard States
The free energy change for a process taking place with reactants and products present under nonstandard conditions (pressures other than 1 bar; concentrations other than 1 M) is related to the standard free energy change according to this equation:
Force and Potential Energy in One Dimension
Force can be calculated from the expression for potential energy, which is a function of position. The component of a conservative force, in a particular direction, equals the negative of the derivative of the corresponding potential energy with respect to the displacement in that direction. For regions where potential energy changes rapidly with displacement, the work done and force is maximum. Also, when force is applied along the positive coordinate axis, the potential energy decreases with...
Energy Diagrams - I
The dynamics of a mechanical system can be easily understood by interpreting a potential energy diagram. Since energy is a scalar quantity, the interpretation of the dynamics of the system becomes even simpler.
Take the example of a skater on a parabolic ramp. The potential energy at different points along the ramp will be proportional to the height of the ramp, which varies quadratically with the horizontal position on the ramp. As the skater moves down the ramp from the highest position,...
Take the example of a skater on a parabolic ramp. The potential energy at different points along the ramp will be proportional to the height of the ramp, which varies quadratically with the horizontal position on the ramp. As the skater moves down the ramp from the highest position,...
Energy Diagrams - II
Energy diagrams are important to understand the dynamics of a system. The topology of an energy diagram helps illustrate the equilibrium points of the system.
The point in the energy diagram at which the system’s potential energy is the lowest is known as the local minima. The system tends to stay in this position indefinitely unless acted upon by a net force. The slope of the potential energy diagram at the local minima is zero, indicating that zero net force is acting on the system. The slope...
The point in the energy diagram at which the system’s potential energy is the lowest is known as the local minima. The system tends to stay in this position indefinitely unless acted upon by a net force. The slope of the potential energy diagram at the local minima is zero, indicating that zero net force is acting on the system. The slope...
Atomic Nuclei: Nuclear Spin State Overview
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
The Molecular Nature of Internal Energy
The internal energy of a molecule is determined by its degrees of freedom, including translational, rotational, and vibrational motions. In addition to these kinetic activities, the energy of molecules is also shaped by electronic energy, intermolecular forces, and the rest-mass energy of electrons and nuclei. These factors collectively influence the energy state of the molecules. The equipartition theorem of classical mechanics provides insight into this energy distribution. It posits that the...

