Publications by authors named "Michael Esch"

Background/purpose: Several methods are used to evaluate the outcome of total hip arthroplasty (THA), however, their relationship at different time points after surgery is unclear. The purpose of this exploratory study was to investigate correlations between self-report function, performance-based tests (PBTs) and biomechanical parameters in patients 12 months after THA.

Methods: Eleven patients were included in this preliminary cross-sectional study.

View Article and Find Full Text PDF

In mixed quantum-classical nonadiabatic molecular dynamics methods, the anchoring of the electronic wave function to a single nuclear geometry results in both quantitative and qualitative errors in the dynamics. In the context of both Ehrenfest and trajectory surface hopping methods, methods for incorporating decoherence are widely used to eliminate these errors. However, the accuracy of these methods often depends strongly on the parameterization of the decoherence time and/or other related quantities.

View Article and Find Full Text PDF

The complete active space self-consistent field (CASSCF) method has seen broad adoption due to its ability to describe the electronic structure of both the ground and excited states of molecules over a broader swath of the potential energy surface than is possible with the simpler Hartree-Fock approximation. However, it also has a reputation for being unwieldy, computationally costly, and un-black-box. Here, we discuss a class of alternatives, complete active space configuration interaction (CASCI) methods, paying particular attention to their application to electronic excited states.

View Article and Find Full Text PDF

Decoherence corrections increase the accuracy of mixed quantum-classical nonadiabatic molecular dynamics methods, but they typically require explicit knowledge of the potential energy surfaces of all occupied electronic states. This requirement renders them impractical for applications in which large numbers of electronic states are occupied. The authors recently introduced the collapse to a block (TAB) decoherence correction [M.

View Article and Find Full Text PDF

Independent trajectory (IT) nonadiabatic molecular dynamics simulation methods are powerful tools for modeling processes involving transitions between electronic states. Incorporation and refinement of decoherence corrections into popular IT methods, e.g.

View Article and Find Full Text PDF

A predictive theory connecting atomic structure to the rate of recombination would enable the rational design of semiconductor nanomaterials for optoelectronic applications. Recently our group has demonstrated that the theoretical study of conical intersections can serve this purpose. Here we review recent work in this area, focusing on the thesis that low-energy conical intersections in nanomaterials share a common feature: locality.

View Article and Find Full Text PDF

The utility of optoelectronic materials can be greatly reduced by the presence of efficient pathways for nonradiative recombination (NRR). Lead halide perovskites have garnered much attention in recent years as materials for solar energy conversion, because they readily absorb visible light, are easy to synthesize, and have a low propensity for NRR. Here we report a theoretical study of the pathways for NRR in an archetypal lead halide perovskite: CsPbBr.

View Article and Find Full Text PDF

The ability to predict and describe nonradiative processes in molecules via the identification and characterization of conical intersections is one of the greatest recent successes of theoretical chemistry. Only recently, however, has this concept been extended to materials science, where nonradiative recombination limits the efficiencies of materials for various optoelectronic applications. In this review, we present recent advances in the theoretical study of conical intersections in semiconductor nanomaterials.

View Article and Find Full Text PDF

The optically populated excited state wave packet propagates along multidimensional intramolecular coordinates soon after photoexcitation. This action occurs alongside an intermolecular response from the surrounding solvent. Disentangling the multidimensional convoluted signal enables the possibility to separate and understand the initial intramolecular relaxation pathways over the excited state potential energy surface.

View Article and Find Full Text PDF