A Classical Description of the Radiating Cavity Model in Quantum Mechanics

Consider a quantum particle of mass M in R3, described at time 0 by a wave function ϕ(x) with dispersion Δ, interacting independently with a collection of N particles of mass m. Using only Schroedinger's Quantum Mechanics we prove that when N becomes large and m/M becomes small, and if the information at time t>0 about the N particles of small mass in negleted, the system admits a "classical" description, i.e. a description in which the coherence of the wave function over distances of the order of mM-1N-1Δ have disappeared. We consider this a first step towards proving that most "sufficiently large" quantum systems interacting with an uncontrolled environment admit a classical description at least for position measurements.

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Deterministic Quantum Mechanics: Classical nuclear motion explains chemical reactions and spectra

10.22541/au.163488981.14531614/v1 ◽

2021 ◽

Author(s):

Erik Rohloff ◽

Dominik Rudolph ◽

Onno Strolka ◽

Irmgard Frank

Keyword(s):

Molecular Dynamics ◽

Quantum Mechanics ◽

Infrared Spectrum ◽

Chemical Reactions ◽

Noble Gas ◽

Quantum Effects ◽

Nuclear Motion ◽

Classical Description ◽

Special Environment ◽

Nuclear Quantum Effects

Is a classical description of nuclear motion sufficient when describing chemical reactions? The present paper investigates some phenomena that were previously attributed to nuclear quantum effects. The aim is to show that these phenomena can be modelled with traditional Car-Parrinello molecular dynamics, that is, with a method which treats nuclear motion classically. We find that no additional paradigm is needed for describing chemical reactions. The special reactivity observed for carbenes can be attributed to the special environment represented by a noble gas matrix. Also the infrared spectrum of porphycene is perfectly modelled by traditional Car-Parrinello molecular dynamics. If no more convincing examples are produced, one will stick to deterministic quantum mechanics, as it is the simpler theory which, in addition, is free of paradoxa.

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