ABSTRACT
Direct atomistic simulation of nonadiabatic molecular dynamics is a challenging goal that allows important insights into fundamental physical phenomena. A variety of frameworks, ranging from fully quantum treatment of nuclei to semiclassical and mixed quantum-classical approaches, were developed. These algorithms are then coupled to specific electronic structure techniques. Such diversity and lack of standardized implementation make it difficult to compare the performance of different methodologies when treating realistic systems. Here, we compare three popular methods for large chromophores: Ehrenfest, surface hopping, and multiconfigurational Ehrenfest with ab initio multiple cloning (MCE-AIMC). These approaches are implemented in the NEXMD software, which features a common computational chemistry model. The resulting comparisons reveal the method performance for population relaxation and coherent vibronic dynamics. Finally, we study the numerical convergence of MCE-AIMC algorithms by considering the number of trajectories, cloning thresholds, and Gaussian wavepacket width. Our results provide helpful reference data for selecting an optimal methodology for simulating excited-state molecular dynamics.
ABSTRACT
BACKGROUND: While the preferred surgical treatment for chronic periprosthetic joint infection (PJI) in North America is a 2-stage exchange arthroplasty, the optimal time between first-stage and reimplantation surgery remains unknown. This study was conceived to examine the association between time to reimplantation and treatment failure. METHODS: Using an institutional database, we identified PJI cases treated with 2-stage exchange arthroplasty between 2000 and 2016. Musculoskeletal Infection Society criteria were used to define PJI, and treatment failure was defined using Delphi criteria. The interstage interval between first-stage and reimplantation surgery for each case was collected, alongside demographics, patient-related and organism-specific data. Multivariate logistic regression analyses were used to examine association with treatment failure. RESULTS: Our final analysis consisted of 282 patients with an average time to reimplantation of 100.2 days (range, 20-648). Sixty-three patients (22.3%) failed at 1 year based on Delphi criteria. Time to reimplantation was not significantly associated with failure in both univariate (P = .598) and multivariate (P = .397) models. However, patients reimplanted at >26 weeks were twice as likely to fail in comparison to those reimplanted within <26 weeks (43.8% vs 21.1%), and this finding reached marginal significance (P = .057). Patients who failed had significantly more comorbidities (P = .008). Charlson comorbidity index was the only variable significantly associated with treatment failure in regression analysis (odds ratio, 1.40; 95% confidence interval, 1.06-1.86; P = .019). CONCLUSION: The length of the interstage interval was not a statistically significant predictor of failure in patients undergoing 2-stage exchange arthroplasty for PJI.