Related Experiment Video
Updated: Feb 16, 2026
10:40
High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
8.0K
Mixed quantum/semiclassical wave-packet dynamical method for condensed-phase molecular spectroscopy signals.
Philip A Kovac1, Jeffrey A Cina1
1Department of Chemistry and Biochemistry, and Oregon Center for Optical, Molecular, and Quantum Science, University of Oregon, Eugene, Oregon 97403, USA.
The Journal of Chemical Physics
|December 17, 2017
Summary
A new mixed quantum/semiclassical wave-packet dynamical theory accurately calculates spectroscopic signals for molecules in cryogenic environments. This variational fixed vibrational basis/Gaussian bath (FVB/GB) theory provides precise linear absorption spectra, even with complex system-bath interactions.
Area of Science:
- Quantum dynamics
- Spectroscopy
- Computational chemistry
Background:
- Calculating spectroscopic signals for molecules in cryogenic environments is computationally challenging.
- Existing methods struggle to accurately model complex system-bath interactions.
Purpose of the Study:
- To apply a novel mixed quantum/semiclassical wave-packet dynamical theory to calculate the linear absorption spectrum.
- To assess the accuracy of the variational fixed vibrational basis/Gaussian bath (FVB/GB) theory in a realistic scenario.
Main Methods:
- Employed a mixed quantum/semiclassical wave-packet dynamical theory (FVB/GB).
- Assumed time scale separation between high-frequency system motions and slower bath motions.
- Treated system dynamics with basis-set methods and bath dynamics with a semiclassical, thawed Gaussian trial form.
- Applied the theory to an iodine-krypton cluster model.
Main Results:
- Successfully calculated the linear absorption spectrum of a small-molecule chromophore in a cryogenic environment.
- Achieved an accuracy of approximately 15 cm-1 resolution.
- Demonstrated the theory's ability to handle thousands of spectral lines and system-bath resonances.
Conclusions:
- The FVB/GB theory is a successful and accurate method for calculating spectroscopic signals.
- The theory effectively models complex interactions in cryogenic environments.
- This approach offers a reliable tool for studying molecular spectroscopy.
Related Concept Videos
01:14Molecular Spectroscopy: Absorption and Emission
4.7K
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.
4.7K
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.6K
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...
1.6K
02:32The de Broglie Wavelength
33.8K
In the macroscopic world, objects that are large enough to be seen by the naked eye follow the rules of classical physics. A billiard ball moving on a table will behave like a particle; it will continue traveling in a straight line unless it collides with another ball, or it is acted on by some other force, such as friction. The ball has a well-defined position and velocity or well-defined momentum, p = mv, which is defined by mass m and velocity v at any given moment. This is the typical...
33.8K
02:35Molecular Orbital Theory I
47.8K
Overview of Molecular Orbital Theory
47.8K
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
3.0K
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...
3.0K
02:45The Quantum-Mechanical Model of an Atom
59.8K
Shortly after de Broglie published his ideas that the electron in a hydrogen atom could be better thought of as being a circular standing wave instead of a particle moving in quantized circular orbits, Erwin Schrödinger extended de Broglie’s work by deriving what is now known as the Schrödinger equation. When Schrödinger applied his equation to hydrogen-like atoms, he was able to reproduce Bohr’s expression for the energy and, thus, the Rydberg formula governing hydrogen spectra.
59.8K