144 citations · 591 across the 17 of their papers we have counts for
19 papers
Equilibrating continuous-variable open quantum systems using stochastic classical trajectories in path-integral space
William H. D. Moore, Stuart C. Althorpe
Beyond the weak-coupling limit, open quantum systems equilibrate to a highly entangled thermal state. For continuous-variable systems, this state can be written explicitly as an im…
Exploiting the path-integral radius of gyration in open quantum dynamics
Andrew C. Hunt, Stuart C. Althorpe
A major challenge in open quantum dynamics is the inclusion of Matsubara-decay terms in the memory kernel, which arise from the quantum-Boltzmann delocalisation of the bath modes.…
Effective classical potential for quantum statistical averages
Vijay Ganesh Sadhasivam, Stuart C. Althorpe, Venkat Kapil
We present an effective potential that allows quantum thermal expectation values of a position-dependent observable to be estimated as a classical ensemble average of the correspon…
On the origin of exponential operator growth in Hilbert space
Vijay Ganesh Sadhasivam, Jan M. Rost, Stuart C. Althorpe
The question of thermalization in quantum many-body systems has long been studied through the properties of matrix elements of operators corresponding to local observables. More re…
Quantum rates in dissipative systems with spatially varying friction
Oliver Bridge, Paolo Lazzaroni, Rocco Martinazzo +3
We investigate whether making the friction spatially dependent on the reaction coordinate introduces quantum effects into the thermal reaction rates for dissipative reactions. Quan…
Thermal quenching of classical and semiclassical scrambling
Vijay Ganesh Sadhasivam, Andrew C. Hunt, Lars Meuser +2
Quantum scrambling often gives rise to short-time exponential growth in out-of-time-ordered correlators (OTOCs). The scrambling rate over an isolated saddle point at finite tempera…
Instantons and the quantum bound to chaos
Vijay Ganesh Sadhasivam, Lars Meuser, David R. Reichman +1
We investigate why the Lyapunov exponents of out-of-time-ordered correlators (OTOCs) satisfy a universal bound by probing imaginary-time path-integral spa…
Comparison of Matsubara dynamics with exact quantum dynamics for an oscillator coupled to a dissipative bath
Adam Prada, Eszter S. Pós, Stuart C. Althorpe
Matsubara dynamics is the classical dynamics which results when imaginary-time path-integrals are smoothed; it conserves the quantum Boltzmann distribution and appears in drastical…
Improved torque estimator for condensed-phase quasicentroid molecular dynamics
George Trenins, Christopher Haggard, Stuart C. Althorpe
We describe improvements to the quasicentroid molecular dynamics (QCMD) path-integral method, which was developed recently for computing the infrared spectra of condensed-phase sys…
Testing the quasicentroid molecular dynamics method on gas-phase ammonia
Christopher Haggard, Vijay Ganesh Sadhasivam, George Trenins +1
Quasicentroid molecular dynamics (QCMD) is a path-integral method for approximating nuclear quantum effects in dynamics simulations, which has given promising results for gas- and…
Path-integral dynamics of water using curvilinear centroids
George Trenins, Michael J. Willatt, Stuart C. Althorpe
We develop a path-integral dynamics method for water that resembles centroid molecular dynamics (CMD), except that the centroids are averages of curvilinear, rather than cartesian,…
Mean-field Matsubara dynamics: Analysis of path-integral curvature effects in rovibrational spectra
George Trenins, Stuart C. Althorpe
It was shown recently that smooth and continuous "Matsubara" phase-space loops follow a quantum-Boltzmann-conserving classical dynamics when decoupled from non-smooth distributions…
Tunneling-splittings from path-integral molecular dynamics using a Langevin thermostat
C L Vaillant, D J Wales, S C Althorpe
We report an improved method for the calculation of tunneling splittings between degenerate configurations in molecules and clusters using path-integral molecular dynamics (PIMD).…
An alternative derivation of ring-polymer molecular dynamics transition-state theory
Timothy J. H. Hele, Stuart C. Althorpe
In a previous article [J. Chem. Phys. 138, 084108 (2013)], we showed that the limit of ring-polymer molecular dynamics (RPMD) rate-theory is also the limit of…
Relation of centroid molecular dynamics and ring-polymer molecular dynamics to exact quantum dynamics
Timothy J. H. Hele, Michael J. Willatt, Andrea Muolo +1
We recently obtained a quantum-Boltzmann-conserving classical dynamics by making a single change to the derivation of the `Classical Wigner' approximation. Here, we show that the f…
Boltzmann-conserving classical dynamics in quantum time-correlation functions: Matsubara dynamics
Timothy J. H. Hele, Michael J. Willatt, Andrea Muolo +1
We show that a single change in the derivation of the linearized semiclassical-initial value representation (LSC-IVR or classical Wigner approximation) results in a classical dynam…
Derivation of a true (t->0+) quantum transition-state theory. Part I: Uniqueness and equivalence to ring-polymer molecular dynamics transition-state-theory
Timothy J. H. Hele, Stuart C. Althorpe
Surprisingly, there exists a quantum flux-side time-correlation function which has a non-zero short-time (t->0+) limit, and thus yields a rigorous quantum generalization of classic…
On the uniqueness of t->0+ quantum transition-state theory
Timothy J. H. Hele, Stuart C. Althorpe
It was shown recently that there exists a true quantum transition-state theory (QTST) corresponding to the t->0+ limit of a (new form of) quantum flux-side time-correlation functio…
Derivation of a true (t->0+) quantum transition-state theory. II. Recovery of the exact quantum rate in the absence of recrossing
Stuart C. Althorpe, Timothy J. H. Hele
In Part I [J. Chem. Phys. 138, 084108 (2013)] we derived a quantum transition-state theory by taking the t->0+ (short-time) limit of a new form of quantum flux-side time-correlatio…