scholarly journals Investigation of transition symmetry shapes of 160-168Yb nuclei using IBM

2021 ◽  
pp. 1135-1143
Author(s):  
Heiyam Najy Hady ◽  
Mohsin Kadhim Muttalb
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Transition Probability ◽  
Electric Quadrupole ◽  
Gradual Transition ◽  
Contour Plot ◽  
Electric Quadrupole Transition ◽  
Complete Study ◽  
Energy Ratios

The interacting boson models,  and  were used to perform a complete study  of even –even 160-168Yb isotopes .The low –lying positive parity states, dynamic symmetries, reduced electric quadrupole transition probability , quadruple  momentum , and potential energy surface  for 160-168Yb  were investigated. Energy level sequences and energy ratios showed the gradual transition of the properties of these nuclei from the γ-unstable features  to the rotational features . Adding the pairing parameter  to   Hamiltonian had a very slight effect on this feature, but it raised the β band, since it represents symmetry breaking such as in γ-unstable features . This applies to the experimental decay scheme  of 160-168Yb isotopes. In , proton and neutron quadruple deformation parameters  and  showed values equal to -1.24 and approximately 0.7, respectively, which supports the same idea in the interacting boson model . A contour plot of  the potential energy surface for 160-168Yb isotopes showed that the minimum potential occurs at approximately .

scholarly journals SU(3) Symmetry in hafnium isotopes with even neutron N=100-108

2020 ◽  
Vol 9 (2) ◽  
pp. 142
Author(s):  
I. Hossain ◽  
Fadhil I. Sharrad ◽  
Huda H. Kassim ◽  
Amir A. Mohammed-Ali ◽  
A. S. Ahmed
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Transition Probabilities ◽  
Dynamical Symmetry ◽  
Electric Quadrupole ◽  
Transition Strength ◽  
Quadrupole Moments ◽  
Hafnium Isotopes ◽  
Reduced Transition Probabilities

In this paper, we have reviewed the calculation of ground states energy level up to spin 14+, electric quadrupole moments up to spin 12+, and reduced transition probabilities of Hafnium isotopes with even neutron N = 100-108 by Interacting Boson Model (IBM-1). The calculated results are compared with previous available experimental data and found good agreement for all nuclei. Moreover, we have studied potential energy surface of those nuclei. The systematic studies of quadrupole moments, reduced transition strength, yrast level and potential energy surface of those nuclei show an important property that they are deformed and have dynamical symmetry SU(3) characters.

scholarly journals Theoretical calculation of a full-dimensional ab initio potential energy surface and prediction of infrared spectra for Xe–CS2

RSC Advances ◽  
2019 ◽  
Vol 9 (36) ◽  
pp. 20925-20930
Author(s):  
Miao Qin ◽  
Xiuchan Xiao ◽  
Hua Zhu
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Theoretical Calculation ◽  
Infrared Spectra ◽  
Energy Surface ◽  
Intermolecular Potential ◽  
Contour Plot

Contour plot (in cm−1) of the averaged intermolecular potential energy surface for Xe–CS2 with CS2 at the ν1 + ν3 excited state.

scholarly journals Calculate Energy Levels, Energy Ratios and Electric Quadrupole Transition Probability B(E2), of the Even-Even Yb-164 Isotopes Using IBM-1

2020 ◽  
Vol 31 (1) ◽  
pp. 71
Author(s):  
Sallama Sadiq Hummadi ◽  
Omar Ahmed M. Safauldeen ◽  
Amani Abdullah Kumeel ◽  
Anaam Musa Hadee ◽  
Raghdaa Hameed Honi
Keyword(s):  
Transition Probability ◽  
Energy Levels ◽  
Dynamical Symmetry ◽  
Electric Quadrupole ◽  
Quadrupole Transition ◽  
Electric Quadrupole Transition ◽  
Energy Ratios ◽  
Boson Model ◽  
Acceptable Agreement

The nuclear structure for even-even nuclei  estimated by using interacting boson model (IBM-1). Also this program was used to determine energy levels of g- state, energy ratios and electric quadrupole transitions probability B(E2) which have been calculated. Depending on the follow up of energy ground bands (g, β, and γ) . The dynamical symmetry and energy spectrum of selected isotope are determined by B(E2). The electric quadrupole transition probability of the (2ᶢ+-0ᶢ+) transitions for Yb (A=164) isotopes with the dynamical symmetry SU(3)- SU(5) from rotational SU(3) to vibrational SU(5). All obtained results of the study were compared with experimental facts and acceptable agreement obtained.

Active Learning Accelerates Ab Initio Molecular Dynamics on Pericyclic Reactive Energy Surfaces

2020 ◽  
Author(s):  
Shi Jun Ang ◽  
Wujie Wang ◽  
Daniel Schwalbe-Koda ◽  
Simon Axelrod ◽  
Rafael Gomez-Bombarelli
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Transition State ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Computational Cost ◽  
Reactive Trajectories ◽  
Dynamics Simulations ◽  
Energy Surfaces

<div>Modeling dynamical effects in chemical reactions, such as post-transition state bifurcation, requires <i>ab initio</i> molecular dynamics simulations due to the breakdown of simpler static models like transition state theory. However, these simulations tend to be restricted to lower-accuracy electronic structure methods and scarce sampling because of their high computational cost. Here, we report the use of statistical learning to accelerate reactive molecular dynamics simulations by combining high-throughput ab initio calculations, graph-convolution interatomic potentials and active learning. This pipeline was demonstrated on an ambimodal trispericyclic reaction involving 8,8-dicyanoheptafulvene and 6,6-dimethylfulvene. With a dataset size of approximately</div><div>31,000 M062X/def2-SVP quantum mechanical calculations, the computational cost of exploring the reactive potential energy surface was reduced by an order of magnitude. Thousands of virtually costless picosecond-long reactive trajectories suggest that post-transition state bifurcation plays a minor role for the reaction in vacuum. Furthermore, a transfer-learning strategy effectively upgraded the potential energy surface to higher</div><div>levels of theory ((SMD-)M06-2X/def2-TZVPD in vacuum and three other solvents, as well as the more accurate DLPNO-DSD-PBEP86 D3BJ/def2-TZVPD) using about 10% additional calculations for each surface. Since the larger basis set and the dynamic correlation capture intramolecular non-covalent interactions more accurately, they uncover longer lifetimes for the charge-separated intermediate on the more accurate potential energy surfaces. The character of the intermediate switches from entropic to thermodynamic upon including implicit solvation effects, with lifetimes increasing with solvent polarity. Analysis of 2,000 reactive trajectories on the chloroform PES shows a qualitative agreement with the experimentally-reported periselectivity for this reaction. This overall approach is broadly applicable and opens a door to the study of dynamical effects in larger, previously-intractable reactive systems.</div>

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