The modified version of second and fourth order vibrational perturbation theory, whereby the Euclidean action for tunneling is computed on the inverted potential at a shifted energy that is ℏ2 dependent, is applied to a symmetric double well quartic potential. The mean energies of the doublets in each well are also computed using vibrational perturbation theory. Results show that the modified vibrational perturbation theory significantly improves the estimates of tunneling splitting energies both for the ground state and for excited state doublets.
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http://dx.doi.org/10.1063/5.0220517 | DOI Listing |
Spectrochim Acta A Mol Biomol Spectrosc
January 2025
Laboratory for Spectroscopy, Molecular Modeling and Structure Determination, Institute of Nuclear Chemistry and Technology, 16 Dorodna Street, 03-195 Warsaw, Poland. Electronic address:
The Raman spectra of lanthanide [Ln(HO)(Ala)](ClO) crystals were measured with 488, 532, 633, and 1064 nm laser lines, and ROA of complexes in water were collected using 532 nm excitation. As in IR and VCD, ν(CO) stretching and β(OCO) bending vibration bands showed a tendency typical to the lanthanide contraction effect. However, in Raman, the effect is less pronounced than the IR spectrum because it is strongly perturbed by lanthanide ion luminescence, which comes from the 4f → 4f transitions.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Center for Computational Molecular Science and Technology, School of Chemistry and Biochemistry, and School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.
We present pyVPT2, a program to perform second-order vibrational perturbation theory (VPT2) computations to obtain anharmonic vibrational frequencies. This program is written in Python and can utilize any of the several quantum chemistry programs that have been interfaced to the QCEngine project of the Molecular Sciences Software Institute (MolSSI). The requisite single point energy, gradient, or Hessian computations can be automatically performed in a distributed-parallel fashion by optionally using the MolSSI's QCFractal software.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Department of Chemistry, University of California, Davis, One Shields Ave., Davis, California 95616, United States.
Combustion and pyrolysis processes of allene and propyne are known to involve radicals with the structural formula CH, the most stable of which is the classic resonance-stabilized allyl radical. In addition to allyl, four other isomers of CH are possible: the propene derivatives -1-propenyl, -1-propenyl, and 2-propenyl, as well as the cyclopropane derivative cyclopropyl. Among these 5 species, the allyl radical has been extensively studied both theoretically and spectroscopically; however, little is known about the spectroscopy of the cyclopropyl radical, and virtually no experimental spectroscopic data are available for the remaining three.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264000, China.
Constructing multifunctional phosphors grounded in the intricate relationship between energy level structures and luminescent properties has captivated researchers in the luminescent material field. Herein, using the embedded cluster multiconfigurational ab initio method, the energy levels of Bi in the SrLaGaO host at different geometries were calculated, which results in the establishment of complete configurational coordinate curves, yielding breathing mode vibrational frequencies and equilibrium bond lengths for all excited states. These curves supply deep insight into the luminescence properties of Bi-doped phosphors and highlight the impact of ions in the second coordination sphere on luminescence.
View Article and Find Full Text PDFNano Lett
January 2025
Department of Engineering Mechanics, Zhejiang University, Hangzhou, 310027 Zhejiang, China.
Chiral vortices and their phase transition in ferroelectric/dielectric heterostructures have drawn significant attention in the field of condensed matter. However, the dynamical origin of the chiral phase transition from achiral to chiral polar vortices has remained elusive. Here, we develop a phase-field perturbation model and discover the softening of out-of-plane vibration mode of polar vortices in [(PbTiO)/(SrTiO)] superlattices at a critical epitaxial strain or temperature.
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