Multiscale Simulations of Brittle Fracture and the Quantum-Mechanical Nature of Bonding in Silicon

2000 ◽  
Vol 653 ◽  
Author(s):  
N. Bernstein ◽  
D. Hess
2000 ◽  
Vol 653 ◽  
Author(s):  
N. Bernstein ◽  
D. Hess

AbstractWe simulate the microscopic details of brittle fracture in silicon by dynamically coupling empirical-potential molecular dynamics of a strained sample to a quantum-mechanical description of interatomic bonding at the crack tip. Our simulations show brittle fracture at loads comparable to experiment, in contrast with empirical potential simulations that show only ductile crack propagation at much higher loading. While the ductility of the empirical potentials can be attributed to their short range, it is unclear whether the increased range of the tight-binding description is sufficient to explain its brittle behavior. Using the multiscale method we show that at a temperature of 1100 K, but not at 900 K, a dislocation is sometimes nucleated when the crack tip impinges on a vacancy. While this result is too limited in length and time scales to directly correspond to experimental observations, it is suggestive of the experimentally observed brittle to ductile transition.


2020 ◽  
Author(s):  
Ajay Agarwal

The state of reality is not bound by the state of progress. Irrespective of our association, or lack of it, with any school of philosophy, the notion that we witness society and the events that occur within it cannot be denied. Consequently, the inception of a significant altercation in the existing direction of any perception regarding an unexplained phenomenon must involve the realization of a requirement for altercation (be it minor or major) to the direction of research conducted in the same. The identification of the correct altercation, hence, becomes the only topic of debate. The process of this identification requires a stoic sense of review of the current state of research and the current state of question that we wish to address. Therefore, it becomes important that this entity must be free from all forms of existing bias and must implement the existing approaches available without the limitations of the subject they are defined in. In this paper, I aim to do the same. This paper presents a thought experiment that eventually paves the way for establishing a quantum mechanical model for interpreting the notion of the Dark Triad whilst addressing all the concerns mentioned in Miller et al. (2019) regarding the current state of research in the field. The frequent question of identification of any empirical proof is rendered moot for this model given its vast intuitive appeal and philosophical foundation. While the author welcomes any attempts possible to provide solid, empirical proof of this quantum Dark Triad model, it is to be noted that the author considers attempts for the same to take into consideration the questions of formalism and determinism as expected from any scientific theory.


An account is given of the way symmetry is incorporated into string theory by using the Frenkel—Kac—Segal mechanism, taken from the representation theory of affine Kac-Moody algebras. The intrinsically quantum mechanical nature of this mechanism is emphasized, and the present stage of development of string theory is compared with the ‘old quantum theory’. The corresponding method of incorporating gauge symmetry into superstring theories is discussed and arguments that appear to prevent the construction of realistic theories of this type are reviewed in outline.


2002 ◽  
Vol 38 (3) ◽  
pp. 305-308 ◽  
Author(s):  
Long Gui-Lu ◽  
Yan Hai-Yang ◽  
Li Yan-Song ◽  
Tu Chang-Cun ◽  
Zhu Sheng-Jiang ◽  
...  

2020 ◽  
Vol 17 (supp01) ◽  
pp. 2040005
Author(s):  
Massimo Blasone ◽  
Giuseppe Vitiello

The study of the damped harmonic oscillator shows that dissipation could be seen at the origin of the zero point energy, which is the signature of quantum behavior. This is in accord with ’t Hooft proposal that loss of information in a completely deterministic dynamics would play a rôle in the quantum mechanical nature of our world. We show the equivalence, within quite general conditions, between the pair of a damped oscillator and its time-reversed image and electrodynamics. The ground state of the damped-amplified oscillator pair appears to be a finite temperature coherent two-mode squeezed state with fractal self-similarity properties and the modes are maximally entangled. Temperature is strictly related to the zero point energy.


Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 219
Author(s):  
Andrew A. Zhuravlev ◽  
Karine K. Abgaryan ◽  
Dmitry L. Reviznikov

A multiscale approach to discrete element modeling is presented. A distinctive feature of the method is that each macroscopic discrete element has an associated atomic sample representing the material’s atomic structure. The dynamics of the elements on macro and micro levels are described by systems of ordinary differential equations, which are solved in a self-consistent manner. A full cycle of multiscale simulations is applied to polycrystalline silicon. Macroscale elastic properties of silicon were obtained only using data extracted from the quantum mechanical properties. The results of computational experiments correspond well to the reference data.


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