scholarly journals Mode specific dynamics of the H2 + CH3 → H + CH4 reaction studied using quasi-classical trajectory and eight-dimensional quantum dynamics methods

2015 ◽  
Vol 143 (15) ◽  
pp. 154307 ◽  
Author(s):  
Yan Wang ◽  
Jun Li ◽  
Liuyang Chen ◽  
Yunpeng Lu ◽  
Minghui Yang ◽  
...  
Keyword(s):  
Quantum Dynamics ◽  
Classical Trajectory

COMPARATIVE STUDY OF REACTION RATE CONSTANTS FOR THE NH3 + H → NH2 + H2 REACTION WITH GLOBE DYNAMICS AND TRANSITION STATE THEORIES

2009 ◽  
Vol 08 (06) ◽  
pp. 1227-1233 ◽  
Author(s):  
JU LIPING ◽  
LU RUIFENG
Keyword(s):  
Transition State ◽  
Cross Sections ◽  
Rate Constants ◽  
Quantum Dynamics ◽  
Classical Trajectory ◽  
State Theory ◽  
Title Reaction ◽  
Reaction Rate Constants ◽  
Barrier Type ◽  
Good Agreement

The nine-dimension quasi-classical trajectory (QCT) calculations have been carried out for the title reaction with a global potential energy surface (PES) constructed by Corchado and Espinosa-García (J Chem Phys106:4013, 1997). The detailed dynamics calculations cover the specific collision energies falling in the range of 0.62–3.04 eV, which are sufficient to fit the calculated reactive cross-sections into a barrier-type excitation function and to obtain the thermal rate constants. The present QCT rate constants are in good agreement with the recent quantum dynamics (QD) results, both of which are much lower than that of the previous variational transition state theory (VTST).

WHY IRREVERSIBILITY? THE FORMULATION OF CLASSICAL AND QUANTUM MECHANICS FOR NONINTEGRABLE SYSTEMS

1995 ◽  
Vol 05 (01) ◽  
pp. 3-16 ◽  
Author(s):  
ILYA PRIGOGINE
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Quantum Dynamics ◽  
Probability Distributions ◽  
Classical Trajectory ◽  
Wave Functions ◽  
The Other ◽  
Density Matrices ◽  
The One ◽  
Classical And Quantum Mechanics

Nonintegrable Poincaré systems with continuous spectrum (so-called Large Poincaré Systems, LPS) lead to the appearance of diffusive terms in the framework of dynamics. These terms break time symmetry. They lead, therefore, to limitations to classical trajectory dynamics and of wave functions. These diffusive terms correspond to well-defined classes of dynamical processes (i.e., so-called “vacuum-vacuum” transitions). The diffusive effects are amplified in situations corresponding to persistent interactions. As a result, we have to include already in the fundamental dynamical description the two aspects, probability and irreversibility, which are so conspicuous on the macroscopic level. We have to formulate both classical and quantum mechanics on the Liouville level of probability distributions (or density matrices). For integrable systems, we recover the usual formulations of classical or quantum mechanics. Instead of being irreducible concepts, which cannot be further analyzed, trajectories and wave functions appear as special solutions of the Liouville-von Neumann equations. This extension of classical and quantum dynamics permits us to unify the two concepts of nature we inherited from the 19th century, based on the one hand on dynamical time-reversible laws and on the other on an evolutionary view associated to entropy. It leads also to a unified formulation of quantum theory avoiding the conventional dual structure based on Schrödinger’s equation on the one hand, and on the “collapse” of the wave function on the other. A dynamical interpretation is given to processes such as decoherence or approach to equilibrium without any appeal to extra dynamic considerations (such as the many-world theory, coarse graining or averaging over the environment). There is a striking parallelism between classical and quantum theory. For LPS we have, in general, both a “collapse” of trajectories and of wave functions for LPS. In both cases, we need a generalized formulation of dynamics in terms of probability distributions or density matrices. Since the beginning of this century, we know that classical mechanics had to be generalized to take into account the existence of universal constants. We now see that classical as well as quantum mechanics also have to be extended to include unstable dynamical systems such as LPS. As a result, we achieve a new formulation of "laws of physics" dealing no more with certitudes but with probabilities. The formulation is appropriate to describe an open, evolving universe.

Mode specific dynamics in the H2 + SH → H + H2S reaction

2016 ◽  
Vol 18 (42) ◽  
pp. 29113-29121 ◽  
Author(s):  
Dandan Lu ◽  
Ji Qi ◽  
Minghui Yang ◽  
Jörg Behler ◽  
Hongwei Song ◽  
...  
Keyword(s):  
Quantum Dynamics ◽  
Classical Trajectory ◽  
Mode Selectivity ◽  
Strong Mode

Full-dimensional quantum dynamics and quasi-classical trajectory studies indicate strong mode selectivity in the H2 + SH reaction.

scholarly journals Nonadiabatic ab initio molecular dynamics using linear-response time-dependent density functional theory

Open Physics ◽  
2013 ◽  
Vol 11 (9) ◽  
Author(s):  
Basile Curchod ◽  
Thomas Penfold ◽  
Ursula Rothlisberger ◽  
Ivano Tavernelli
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Ab Initio ◽  
Linear Response ◽  
Quantum Dynamics ◽  
Density Functional ◽  
Classical Trajectory ◽  
Ab Initio Molecular Dynamics ◽  
Nuclear Forces ◽  
Functional Theory

AbstractWe review our recent work on ab initio nonadiabatic molecular dynamics, based on linear-response timedependent density functional theory for the calculation of the nuclear forces, potential energy surfaces, and nonadiabatic couplings. Furthermore, we describe how nuclear quantum dynamics beyond the Born-Oppenheimer approximation can be performed using quantum trajectories. Finally, the coupling and control of an external electromagnetic field with mixed quantum/classical trajectory surface hopping is discussed.

scholarly journals Wave packet dynamics of an atomic ion in a Paul trap

2015 ◽  
Vol 27 (02) ◽  
pp. 1650014 ◽  
Author(s):  
A. Hashemloo ◽  
C. M. Dion ◽  
G. Rahali
Keyword(s):  
Wave Packet ◽  
Quantum Dynamics ◽  
Equations Of Motion ◽  
Center Of Mass ◽  
Paul Trap ◽  
Classical Trajectory ◽  
Time Dependent ◽  
Mass Motion ◽  
Linear Paul Trap ◽  
Wave Packet Dynamics

Using numerical simulations of the time-dependent Schrödinger equation, we study the full quantum dynamics of the motion of an atomic ion in a linear Paul trap. Such a trap is based on a time-varying, periodic electric field and hence corresponds to a time-dependent potential for the ion, which we model exactly. We compare the center-of-mass motion with that obtained from classical equations of motion, as well as to results based on a time-independent effective potential. We also study the oscillations of the width of the ion’s wave packet, including close to the border between stable (bounded) and unstable (unbounded) trajectories. Our results confirm that the center-of-mass motion always follows the classical trajectory, that the width of the wave packet is bounded for trapping within the stability region, and therefore that the classical trapping criterion is fully applicable to quantum motion.

scholarly journals Conical intersection–regulated intermediates in bimolecular reactions: Insights from C(1D) + HD dynamics

2019 ◽  
Vol 5 (4) ◽  
pp. eaaw0446 ◽  
Author(s):  
Yanan Wu ◽  
Jianwei Cao ◽  
Haitao Ma ◽  
Chunfang Zhang ◽  
Wensheng Bian ◽  
...  
Keyword(s):  
Potential Energy Surfaces ◽  
Quantum Dynamics ◽  
Reactive Systems ◽  
Branching Ratios ◽  
Classical Trajectory ◽  
Rate Coefficients ◽  
Deep Well ◽  
Reaction Theory ◽  
Adiabatic Dynamics ◽  
Energy Surfaces

The importance of conical intersections (CIs) in electronically nonadiabatic processes is well known, but their influence on adiabatic dynamics has been underestimated. Here, through combined experimental and theoretical studies, we show that CIs induce a barrier and regulate conversion from a precursor metastable intermediate (CI-R) to a deep well one. This results in bond-selective activation, influencing the adiabatic dynamics markedly in the C(1D) + HD reaction. Theory is validated by experiment; quantum dynamics calculations on highly accurate ab initio potential energy surfaces yield rate coefficients and product branching ratios in excellent agreement with the experiment. Quasi-classical trajectory calculations reveal that the CI-R intermediate leads to unusual reaction mechanisms (designated as C─H activation complex conversion and cyclic complex), which are responsible for large branching ratios. We also reveal that CI-R intermediates exist in other reactive systems, and the dynamical effects uncovered here may have general significance.

THE NOTHING THAT REALLY IS!

2016 ◽  
Vol 12 (1) ◽  
pp. 4172-4177
Author(s):  
Abdul Malek
Keyword(s):  
Quantum Dynamics ◽  
Theoretical Physics ◽  
Historical Evolution ◽  
Proper Understanding ◽  
Physical Universe ◽  
Wave Particle Duality ◽  
Negative Effect ◽  
Materialist Interpretation

The denial of the existence of contradiction is at the root of all idealism in epistemology and the cause for alienations.  This alienation has become a hindrance for the understanding of the nature and the historical evolution mathematics itself and its role as an instrument in the enquiry of the physical universe (1). A dialectical materialist approach incorporating  the role of the contradiction of the unity of the opposites, chance and necessity etc., can provide a proper understanding of the historical evolution of mathematics and  may ameliorate  the negative effect of the alienation in modern theoretical physics and cosmology. The dialectical view also offers a more plausible materialist interpretation of the bewildering wave-particle duality in quantum dynamics (2).

Classical and Quantum Dynamics

1994 ◽  
Author(s):  
Walter Dittrich ◽  
Martin Reuter
Keyword(s):  
Quantum Dynamics
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