Related Experiment Video
Updated: Apr 7, 2026
09:25
Agarose-based Tissue Mimicking Optical Phantoms for Diffuse Reflectance Spectroscopy
Published on: August 22, 2018
12.4K
Comment on: "Toward Accurate Two-Photon Absorption Spectrum Simulations: Exploring the Landscape beyond the
Robin Grotjahn1, Filipp Furche1
1Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, California 92697-2025, United States.
The Journal of Physical Chemistry Letters
|June 13, 2024
Summary
A recent study on two-photon absorption (2PA) strengths using meta-generalized gradient approximation (MGGA) functionals is flawed. It uses an incorrect method and overlooks prior work, leading to inaccurate results for optical properties.
Area of Science:
- Computational Chemistry
- Quantum Chemistry
- Theoretical Chemistry
Background:
- Two-photon absorption (2PA) is a crucial photophysical process.
- Meta-generalized gradient approximation (MGGA) functionals are increasingly used for electronic property calculations.
- Accurate calculation of 2PA strengths is vital for materials science and spectroscopy.
Purpose of the Study:
- To critically evaluate a recent benchmark study (ALRNZ24) on 2PA strengths using MGGA functionals.
- To highlight inaccuracies and methodological flaws in the ALRNZ24 study.
- To recommend appropriate theoretical approaches for calculating optical and magnetic response properties.
Main Methods:
- Review and critique of the methodology employed in the ALRNZ24 study.
- Comparison with previously published benchmark studies on 2PA.
- Analysis of the gauge-dependence of MGGA response theory.
Main Results:
- The ALRNZ24 study misrepresents the current state of 2PA benchmark calculations.
- The gauge-variant MGGA response theory used in ALRNZ24 yields erratic results for specific systems.
- ALRNZ24 failed to acknowledge a prior assessment of the same benchmark.
Conclusions:
- The application of MGGAs to optical and magnetic properties requires gauge-invariant formulations.
- Paramagnetic current-dependent MGGAs are recommended for accurate response property calculations.
- The findings necessitate a re-evaluation of MGGA-based 2PA strength predictions.
More Related Videos
Related Concept Videos
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.7K
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...
1.7K
01:14Molecular Spectroscopy: Absorption and Emission
5.4K
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.
5.4K
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
3.5K
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...
3.5K
01:16IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
3.8K
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...
3.8K
01:23Atomic Spectroscopy: Absorption, Emission, and Fluorescence
3.5K
Atomic spectroscopy is a vital tool in elemental analysis, both qualitatively and quantitatively. It can be broadly divided into optical spectroscopy, mass spectroscopy, and X-ray spectroscopy methods. The optical spectroscopic methods are atomic absorption spectroscopy (AAS), atomic emission spectroscopy (AES), and atomic fluorescence spectroscopy (AFS). The first step in all three methods is atomization, where the solid, liquid, or solution-phase samples are converted into gas-phase atoms and...
3.5K
01:13Atomic Absorption Spectroscopy: Radiation and Light Sources
1.6K
Atomic absorption spectroscopy (AAS) relies on the Beer-Lambert law, which requires that the radiation source emits a narrow range of wavelengths to match the absorption characteristics of the analyte atom. The primary criteria for choosing an appropriate radiation source in AAS is to provide a precise and intense emission at specific wavelengths that will allow accurate detection of the analyte.
Two common narrow-range 'line' sources used in AAS are hollow-cathode lamps (HCLs) and...
Two common narrow-range 'line' sources used in AAS are hollow-cathode lamps (HCLs) and...
1.6K