Software for the frontiers of quantum chemistry:An overview of developments in the Q-Chem 5 package

This article summarizes technical advances contained in the fifth major release of the Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library of exchange–correlation functionals, along with a suite of correlated many-body methods, continues to be a hallmark of the Q-Chem software. The many-body methods include novel variants of both coupled-cluster and configuration-interaction approaches along with methods based on the algebraic diagrammatic construction and variational reduced density-matrix methods. Methods highlighted in Q-Chem 5 include a suite of tools for modeling core-level spectroscopy, methods for describing metastable resonances, methods for computing vibronic spectra, the nuclear–electronic orbital method, and several different energy decomposition analysis techniques. High-performance capabilities including multithreaded parallelism and support for calculations on graphics processing units are described. Q-Chem boasts a community of well over 100 active academic developers, and the continuing evolution of the software is supported by an “open teamware” model and an increasingly modular design

A Comparative Study of SIMULINK 1D Dynamic Model and FLUENT 3D Model for PEMFC Faults Diagnosis

According to the different research platforms of PEMFC (Proton Exchange Membrane Fuel Cell) faults diagnosis, experimental diagnostics and mathematical modeling are employed in the characterization and determination of fuel cell performance. The methods based on mathematical modeling are promised on establishing a suitable model, which is capable to reflect the physical properties of actual fuel cell stack as accurate as possible. Further, a scientific and reasonable PEMFC model is also indispensable for the system performance analysis, design, control, and optimization. Generally, PEMFC auxiliary system adopts a lumped parameter model to provide the boundary conditions of stack, such as current demand, gas flow rate, pressure, and temperature. As PEMFC stack needs to be embedded particular faults in a specific time and space position, it necessitates adopting a distributed parameter model in one dimensional (1D), two dimensional (2D) or three dimensional (3D). In this paper, a comparative analysis is carried out between a diagnostic one dimensional dynamic model by MATLAB/SIMULINK and a diagnostic three dimensional distributed parameter model based on FLUENT. Also, the diagnostic results in specific faults are studied

A Study on PEMFC Performance and Faults Diagnosis Using FLUENT 3D Models

AbstractThe performance and faults diagnosis research on Proton Exchange Membrane Fuel Cell (PEMFC) provide a reliable theoretical and technical support for its commercialization. Meanwhile, PEMFC research based on modeling, which uses the commercial software such as Fluent, SIMULINK etc, affords a theoretical foundation for guiding the experiments and testing the new numerical calculation methods. Hence, based on a single cell 3D (three-dimensional) PEMFC model, the paper studied the performance impacts of physical parameters, such as porosities of GDL, and physical structure, such as the thickness of GDL. Additionally, from the aspect of operating conditions, the cathode gas supply shortage fault is analyzed to study the influence on PEMFC output voltage

A Comparative Study of Equivalent Circuit Models for Electro-Chemical Impedance Spectroscopy Analysis of Proton Exchange Membrane Fuel Cells

Electrochemical impedance spectroscopy is one of the important tools for the performance analysis and diagnosis of proton exchange membrane fuel cells. The equivalent circuit model is an effective method for electrochemical impedance spectroscopy resolution. In this paper, four typical equivalent circuit models are selected to comprehensively compare and analyze the difference in the fitting results of the models for the electrochemical impedance spectroscopy under different working conditions (inlet pressure, stoichiometry, and humidity) from the perspective of the fitting accuracy, change trend of the model parameters, and the goodness of fit. The results show that the fitting accuracy of the model with the Warburg element is the best for all under each working condition. When considering the goodness of fit, the model with constant phase components is the best choice for fitting electrochemical impedance spectroscopy under different inlet pressure and air stoichiometry. However, under different air humidity, the model with the Warburg element is best. This work can help to promote the development of internal state analysis, estimation, and diagnosis of the fuel cell based on the equivalent circuit modeling of electrochemical impedance spectroscopy

Software for the frontiers of quantum chemistry: An overview of developments in the Q-Chem 5 package

This article summarizes technical advances contained in the fifth major release of the Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library of exchange-correlation functionals, along with a suite of correlated many-body methods, continues to be a hallmark of the Q-Chem software. The many-body methods include novel variants of both coupled-cluster and configuration-interaction approaches along with methods based on the algebraic diagrammatic construction and variational reduced density-matrix methods. Methods highlighted in Q-Chem 5 include a suite of tools for modeling core-level spectroscopy, methods for describing metastable resonances, methods for computing vibronic spectra, the nuclear-electronic orbital method, and several different energy decomposition analysis techniques. High-performance capabilities including multithreaded parallelism and support for calculations on graphics processing units are described. Q-Chem boasts a community of well over 100 active academic developers, and the continuing evolution of the software is supported by an "open teamware" model and an increasingly modular design