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

Data from: A trait-based framework for understanding predator-prey relationships: trait matching between a specialist snake and its insect prey

1. High-quality information on predator-prey relationships is fundamental in understanding food webs, community assembly and ecosystem functioning. Recent analytical advances have made it possible to develop new trait-based approaches to study trophic relationships and evaluate trait-matching between predators and prey. 2. Here we develop a novel analytical approach based on generalized linear mixed-effects models (GLMM) to test the importance of prey availability and to identify the set of prey traits that best explain the occurrence and number of prey in the predator’s diet. 3. We demonstrate the approach by using an extensive dataset on prey availability, prey traits, and gut content collected in all known populations of Vipera graeca, a little-known, endangered snake of alpine grasslands in the Pindos Mountains of the Balkan Peninsula.4. We show that V. graeca is a unique, venomous snake specialised on bush-crickets and grasshoppers (Orthoptera). Prey selection GLMMs showed that the ideal prey of V. graeca is abundant, large-bodied, has poor escape abilities (flightless, slow-moving, bad jumper) and prefers loose grasslands (as opposed to bare ground/rock or closed sward). Vipers restrict their feeding to periods of high Orthoptera abundance in the late summer and need to reach a certain body size to become able to catch large-sized prey. 5. Our analytical approach provides a framework for trait matching between predators and prey and unprecedented fine-scale information on the importance of prey traits in prey selection by a specialist predator. The narrow trophic niche of V. graeca likely increases the vulnerability of this cold-adapted snake to extinction

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