scholarly journals Branching Corrected Mean Field Method for Nonadiabatic Dynamics

2020 ◽  
Vol 11 (19) ◽  
pp. 8283-8291
Author(s):  
Jiabo Xu ◽  
Linjun Wang
Keyword(s):  
Mean Field ◽  
Field Method ◽  
Nonadiabatic Dynamics

scholarly journals Branching Corrected Mean Field Method for Nonadiabatic Dynamics

2020 ◽  
Author(s):  
Jiabo Xu ◽  
Linjun Wang
Keyword(s):  
Potential Energy Surfaces ◽  
Quantum Dynamics ◽  
High Efficiency ◽  
Mean Field ◽  
Field Method ◽  
Model Systems ◽  
Nonadiabatic Dynamics ◽  
Model Base ◽  
Dynamics Simulations ◽  
Energy Surfaces

When describing nonadiabatic dynamics based on trajectories, severe trajectory branching occurs when the nuclear wave packets on some potential energy surfaces are reflected while those on the remaining surfaces are not. As a result, the traditional Ehrenfest mean field (EMF) approximation breaks down. In this study, two versions of the branching corrected mean field (BCMF) method are proposed. Namely, when trajectory branching is identified, BCMF stochastically selects either the reflected or the non-reflected group to build the new mean field trajectory or splits the mean field trajectory into two new trajectories with the corresponding weights. As benchmarked in six standard model systems and an extensive model base with two hundred diverse scattering models, BCMF significantly improves the accuracy while retaining the high efficiency of the traditional EMF. In fact, BCMF closely reproduces the exact quantum dynamics in all investigated systems, thus highlighting the essential role of branching correction in nonadiabatic dynamics simulations of general systems.

Quantum Trajectory Mean-Field Method for Nonadiabatic Dynamics in Photochemistry

2019 ◽  
Vol 123 (34) ◽  
pp. 7337-7350 ◽  
Author(s):  
Lin Shen ◽  
Diandong Tang ◽  
Binbin Xie ◽  
Wei-Hai Fang
Keyword(s):  
Mean Field ◽  
Field Method ◽  
Quantum Trajectory ◽  
Nonadiabatic Dynamics

scholarly journals Branching Corrected Mean Field Method for Nonadiabatic Dynamics

2020 ◽  
Author(s):  
Jiabo Xu ◽  
Linjun Wang
Keyword(s):  
Potential Energy Surfaces ◽  
Quantum Dynamics ◽  
High Efficiency ◽  
Mean Field ◽  
Field Method ◽  
Model Systems ◽  
Nonadiabatic Dynamics ◽  
Model Base ◽  
Dynamics Simulations ◽  
Energy Surfaces

When describing nonadiabatic dynamics based on trajectories, severe trajectory branching occurs when the nuclear wave packets on some potential energy surfaces are reflected while those on the remaining surfaces are not. As a result, the traditional Ehrenfest mean field (EMF) approximation breaks down. In this study, two versions of the branching corrected mean field (BCMF) method are proposed. Namely, when trajectory branching is identified, BCMF stochastically selects either the reflected or the non-reflected group to build the new mean field trajectory or splits the mean field trajectory into two new trajectories with the corresponding weights. As benchmarked in six standard model systems and an extensive model base with two hundred diverse scattering models, BCMF significantly improves the accuracy while retaining the high efficiency of the traditional EMF. In fact, BCMF closely reproduces the exact quantum dynamics in all investigated systems, thus highlighting the essential role of branching correction in nonadiabatic dynamics simulations of general systems.

Micromechanics Method to Evaluate Fatigue Life of Ni-Based Superalloys during Morphological Evolution

2008 ◽  
Vol 385-387 ◽  
pp. 221-224
Author(s):  
Wen Ping Wu ◽  
Ya Fang Guo ◽  
Yue Sheng Wang
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Life Prediction ◽  
Morphological Evolution ◽  
Mean Field ◽  
Prediction Method ◽  
Field Method ◽  
External Stress ◽  
Equivalent Inclusion ◽  
Evolution Of Precipitates

A quantitative life prediction method has been proposed to evaluate fatigue life during morphological evolution of precipitates in Ni-based superalloys. The method is essentially based on Eshelby’s equivalent inclusion theory and Mori-Tanaka’s mean field method. The shape stability and life prediction are discussed when the external stress and matrix plastic strain are applied. The calculated results show that the fatigue life is closely related with microstructures evolution of precipitates. The magnitude and sign of the external stress and matrix plastic strain have an important effect on fatigue life of Ni-based superalloys during the morphological evolution of precipitates.

Extended mean-field method for predicting yield behaviors of porous materials

2007 ◽  
Vol 39 (1) ◽  
pp. 53-63 ◽  
Author(s):  
Masakazu Tane ◽  
Tetsu Ichitsubo ◽  
Masahiko Hirao ◽  
Hideo Nakajima
Keyword(s):  
Porous Materials ◽  
Mean Field ◽  
Field Method

The Applicability of the Mean Field Method in the Optical Bistability

1986 ◽  
pp. 173-177
Author(s):  
I. M. Popescu ◽  
E. N. Stefanescu ◽  
P. E. Sterian
Keyword(s):  
Optical Bistability ◽  
Mean Field ◽  
Field Method ◽  
The Mean

Properties of Relativistic Mean-Field Theory

2007 ◽  
Author(s):  
Kenneth G. Dyall ◽  
Knut Faegri
Keyword(s):  
Mean Field Theory ◽  
Mean Field ◽  
Field Method ◽  
Basis Sets ◽  
Electron Interaction ◽  
Relativistic Mean Field ◽  
Dirac Equations ◽  
Electrons And Positrons ◽  
The One ◽  
Atomic Structure Calculations

We have previously seen how the Dirac equation for one particle requires some rather special consideration and interpretation in order to arrive at a form that is able to treat electrons and positrons on an equal footing. These problems persist also when we go to systems with more than one electron. One might think that the extension to several electrons should not introduce dramatic changes. After all, we noted that even the one-electron problem must be viewed as a many-electron (and -positron) system in order to arrive at a consistent description. The problem with introducing more electrons is that electron–electron interactions that were previously small—for the one-electron case typically arising from vacuum polarization and self-interaction—now occur to the same order as the kinetic energy and the interaction with the potential. So while a perturbative approach such as QED can use the solutions of the one-electron Dirac equations as a very good starting approximation to a more accurate description of the full system, the same would not work for a system with more electrons because it would mean neglecting interactions of the same magnitude as the zeroth-order energy. For applications to quantum chemistry, the treatment of the entire electron–electron interaction as a perturbation would be hopelessly impractical, as it is even in manyelectron relativistic atomic structure calculations. The technique for dealing with this problem is well known from nonrelativistic calculations on many-electron systems. One-particle basis sets are developed by considering the behavior of the single electron in the mean field of all the other electrons, and while this neglects a smaller part of the interaction energy, the electron correlation, it provides a suitable starting point for further variational or perturbational treatments to recover more of the electron–electron interaction. It is only natural to pursue the same approach for the relativistic case. Thus one may proceed to construct a mean-field method that can be used as a basis for the perturbation theory of QED.

The Energy Dependence of the Imaginary Nuclear Potential

1985 ◽  
Vol 40 (5) ◽  
pp. 462-465
Author(s):  
Ernst F. Hefter
Keyword(s):  
Conservation Laws ◽  
Energy Dependence ◽  
Specific Energy ◽  
Optical Model ◽  
Mean Field ◽  
Field Method ◽  
Model Potential ◽  
Nuclear Potential ◽  
Optical Model Potential ◽  
Nucleus Scattering

Recently the inverse mean field method (Imefim) has been shown to lead to a specific energy dependence of the real central nuclear part, V, of the optical model potential for nucleon-nucleus scattering. Proceeding from V towards the imaginary volume term of the potential, Wυ, application of conservation laws yields a specific energy dependence for Wυ. It compares favourably with heuristic potentials.

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