9 papers
Born-Oppenheimer, Born-Huang, and exact factorization: quantum geometry and error in analytically transparent benchmark models
Stephen Wiggins
The phrase "potential energy surface" refers to several distinct objects. The Born-Oppenheimer construction gives a clamped-nucleus electronic eigenvalue, the single-surface Born-H…
A Three-Degree-of-Freedom Chesnavich Model for Roaming: Derivation, Phase-Space Geometry, NHIM-Anchored Dividing Surfaces, and Roaming Transport
Stephen Wiggins
Roaming reactions, in which a dissociating fragment moves through a flat region of the potential surface rather than down the minimum-energy path, lie outside the assumptions of co…
An entropic bottleneck, dynamical gating, and outward redistribution of roaming in a designed Chesnavich-type model
Stephen Wiggins
Roaming reactions are organized not by potential-energy saddles but by transition states that are unstable invariant objects in phase space, periodic orbits in the two degrees of f…
Preparation-Space Diagnostics and Logical Information Loss in a Driven Kerr-Cat Qubit
Stephen Wiggins
A Kerr-cat qubit encodes a logical bit in the two wells of a parametrically driven nonlinear oscillator, and a logic gate is a transient change of the drive. In the phase plane the…
A Phase Space Signature of Quantum Roaming in Chesnavich's Model
Stephen Wiggins
Roaming reactions occur when a molecule enters a near-dissociation region, avoids immediate separation, and later forms products by a pathway not controlled by the conventional tig…
Phase Space Bottlenecks in an Adiabatic Marcus Hamiltonian: Cusp Geometry, NHIMs, and Mixed Valence Electron Transfer
Stephen Wiggins
Marcus--Hush theory explains electron transfer in terms of reorganization energies, driving forces, electronic couplings, and reduced free-energy or energy-gap descriptions. These…