Low-temperature chemistry using the R-matrix method

Abstract

Techniques for producing cold and ultracold molecules are enabling the study of chemical reactions and scattering at the quantum scattering limit, with only a few partial waves contributing to the incident channel, leading to the observation and even full control of state-to-state collisions in this regime. A new R-matrix formalism is presented for tackling problems involving low- and ultra-low energy collisions. This general formalism is particularly appropriate for slow collisions occurring on potential energy surfaces with deep wells. The many resonance states make such systems hard to treat theoretically but offer the best prospects for novel physics: resonances are already being widely used to control diatomic systems and should provide the route to steering ultracold reactions. Our R-matrix-based formalism builds on the progress made in variational calculations of molecular spectra by using these methods to provide wavefunctions for the whole system at short internuclear distances, (a regime known as the inner region). These wavefunctions are used to construct collision energy-dependent R-matrices which can then be propagated to give cross sections at each collision energy. The method is formulated for ultracold collision systems with differing numbers of atoms.

Presented at Faraday Discussion on the Theory of Chemical Reactions Published in Faraday Discussions

References in corpus (28)

• Many-Body Physics with Ultracold Gases
• Feshbach Resonances in Ultracold Gases
• Production of cold molecules via magnetically tunable Feshbach resonances
• Evidence for Efimov quantum states in an ultracold gas of cesium atoms
• Quantum-State Controlled Chemical Reactions of Ultracold KRb Molecules
• Experimental Study of the BEC-BCS Crossover Region in Lithium 6
• Laser cooling of a diatomic molecule
• Crossover from a molecular Bose-Einstein condensate to a degenerate Fermi gas
• Creation of ultracold ${}^{87}$RbCs molecules in the rovibrational ground state
• The R-matrix theory
• Laser cooling and slowing of CaF molecules
• Observation of an Efimov-like resonance in ultracold atom-dimer scattering
• Duo: a general program for calculating spectra of diatomic molecules
• Universality of the Three-Body Parameter for Efimov States in Ultracold Cesium
• Evaporative cooling of the dipolar radical OH
• Radio Frequency Association of Efimov Trimers
• Efimov Resonances in Ultracold Quantum Gases
• Feshbach resonances in ultracold atomic and molecular collisions: threshold behaviour and suppression of poles in scattering lengths
• Giant formation rates of ultracold molecules via Feshbach Optimized Photoassociation
• Limits on Universality in Ultracold Three-Boson Recombination
• Inelastic Collisions of Ultracold Polar Molecules
• Broad universal Feshbach resonances in the chaotic spectrum of Dysprosium atoms
• The {\it ab initio} calculation of spectra of open shell diatomic molecules
• Enhancing the Observability of the Efimov Effect in Ultracold Atomic Gas Mixtures
• Dramatic reductions in inelastic cross sections for ultracold collisions near Feshbach resonances
• Efimov Trimer Formation via Ultracold Four-body Recombination
• Ultracold molecular collisions in combined electric and magnetic fields
• Trapping cold ground state argon atoms for sympathetic cooling of molecules

Cited by in corpus (6)

• UKRmol+: a suite for modelling of electronic processes in molecules interacting with electrons, positrons and photons using the R-matrix method
• Perspective: Accurate ro-vibrational calculations on small molecules
• The ExoMol project: Software for computing large molecular line lists
• Momentum space calculations of the binding energies of argon dimer
• Low temperature scattering with the R-matrix method: argon-argon scattering
• Low-temperature scattering with the R-matrix method: from nuclear scattering to atom-atom scattering and beyond