arXiv subjects

Asa Larson

Publications and source records attributed to Asa Larson.

4 recordsLinked to original sources

arXiv2013

A diabatic representation of the two lowest electronic states of Li3

Using the Multi-Reference Configuration Interaction method, the adiabatic potential energy surfaces of Li3 are computed. The two lowest electronic states are bound and exhibit a conical intersection. By fitting the calculated potential energy surfaces to the cubic Exe Jahn-Teller model we extract the effective Jahn-Teller parameters corresponding to Li3. These are used to set up the transformation matrix which transforms from the adiabatic to a diabatic representation. This diabatization method gives a Hamiltonian for Li3 which is free from singular adiabatic couplings and should be accurate for large internuclear distances, and it thereby allows for bound dynamics in the vicinity of the conical intersection to be explored.

physics.chem-ph↗

arXiv2011

Anomalous molecular dynamics in the vicinity of conical intersections

Conical intersections between molecular electronic potential surfaces greatly affect various properties of the molecule. Molecular gauge theory is capable of explaining many of these often unexpected phenomena deriving from the physics of the conical intersection. Here we give an example of anomalous dynamics in the paradigm of the Exe Jahn-Teller model, which does not allow a simple explenation in terms of standard molecular gauge theory. By introducing a dual gauge theory, we unwind this surprising behavior by identifying it with an intrinsic spin Hall effect. Thus, this work link knowledge of condensed matter theories with molecular vibrations. Furthermore, via ab initio calculations the findings are as well demonstrated to appear in realistic systems such as the Li3 molecule.

quant-ph↗

arXiv2008

Quantum interference structures in trapped ion dynamics beyond the Lamb-Dicke and rotating wave approximations

We apply wave packet methods to study an ion-trap system in the strong excitation regime imposing neither the rotating wave nor the Lamb-Dicke approximations. By this approach we show the existence of states with restricted phase space evolution, as a genuine consequence of quantum interference between wave packet fractions. A particular instance of such a state oscillates between maximal entanglement and pure disentanglement between the constitute subsystems. The characteristic crossover time is very rapid making them suitable for state preparations of EPR or Schrodinger cat states. Over longer time periods the dynamics of these states exhibits collapse-revival patterns with well resolved fractional revivals in autocorrelation, inversion and entanglement.

quant-ph↗

arXiv2006

Renner-Teller effects in HCO+ dissociative recombination

A theoretical description of the dissociative recombination process for the HCO+ ion suggests that the nonadiabatic Renner-Teller coupling between electronic and vibrational degrees of freedom plays an important role. This finding is consistent with a recent study of this process for another closed-shell molecule, the H3+ ion, where Jahn-Teller coupling was shown to generate a relatively high rate. The cross section obtained here for the dissociative recombination of HCO+exhibits encouraging agreement with a merged-beam experiment.

physics.atom-ph↗