Size consistent excited states via algorithmic transformations between variational principles

We demonstrate that a broad class of excited state variational principles is not size consistent. In light of this difficulty, we develop and test an approach to excited state optimization that transforms between variational principles in order to achieve state selectivity, size consistency, and compatibility with quantum Monte Carlo. To complement our formal analysis, we provide numerical examples that confirm these properties and demonstrate how they contribute to a more black box approach to excited states in quantum Monte Carlo.Comment: 27 pages, 10 figures, 2 table

Visual detection of point source targets

Visual detection of point source targets in simulated star field backgroun

SNS Timing System

This poster describes the timing system being designed for Spallation Neutron Source being built at Oak Ridge National lab

Tracking excited states in wave function optimization using density matrices and variational principles

We present a method for finding individual excited states' energy stationary points in complete active space self-consistent field theory that is compatible with standard optimization methods and highly effective at overcoming difficulties due to root flipping and near-degeneracies. Inspired by both the maximum overlap method and recent progress in excited state variational principles, our approach combines these ideas in order to track individual excited states throughout the orbital optimization process. In a series of tests involving root flipping, near-degeneracies, charge transfers, and double excitations, we show that this approach is more effective for state-specific optimization than either the naive selection of roots based on energy ordering or a more direct generalization of the maximum overlap method. Furthermore, we provide evidence that this state-specific approach improves the performance of complete active space perturbation theory. With a simple implementation, a low cost, and compatibility with large active space methods, the approach is designed to be useful in a wide range of excited state investigations.Comment: 13 pages, submitted to JCT

European refugee crisis: psychological trauma of refugees and care givers

Purpose – In recent years, the number of refugees and migrants entering Europe has increased dramatically. Such trauma may affect not only refugees themselves, but also care givers and rescue workers. The purpose of this paper is to discuss the intensity and psychological impact of the refugee crisis, with a view to suggesting ways of moving forward. Design/methodology/approach – Based on recent literature, this paper briefly looks at the importance of attention to health and social issues, before discussing the psychological trauma of refugees and potential emotional trauma of those involved in rescue operations. Findings – The provision of psychological support which is both compassionate and culturally competent should be viewed as essential. Furthermore, the development of resources and tools to assist with the current refugee crisis could enable care givers, rescue workers, and healthcare professionals to provide psychological support to migrants and refugees. Such resources could also encourage, and support, frontline responders in caring for their own personal psychological well-being. Originality/value – The content of this paper could help to encourage further research in this field, including research into the emotional trauma of rescue workers. Furthermore, it is intended that this paper could contribute to an on-line knowledge base when considering the development of tools and resources to assist with the current refugee crisis. Keywords Crisis, Refugee, Psychological, Care-givers Paper type General revie

Autonomous Deployment of a Solar Panel Using an Elastic Origami and Distributed Shape Memory Polymer Actuators

Deployable mechanical systems such as space solar panels rely on the intricate stowage of passive modules, and sophisticated deployment using a network of motorized actuators. As a result, a significant portion of the stowed mass and volume are occupied by these support systems. An autonomous solar panel array deployed using the inherent material behavior remains elusive. In this work, we develop an autonomous self-deploying solar panel array that is programmed to activate in response to changes in the surrounding temperature. We study an elastic "flasher" origami sheet embedded in a circle of scissor mechanisms, both printed with shape memory polymers. The scissor mechanisms are optimized to provide the maximum expansion ratio while delivering the necessary force for deployment. The origami sheet is also optimized to carry the maximum number of solar panels given space constraints. We show how the folding of the "flasher" origami exhibits a bifurcation behavior resulting in either a cone or disk shape both numerically and in experiments. A folding strategy is devised to avoid the undesired cone shape. The resulting design is entirely 3D printed, achieves an expansion ratio of 1000% in under 40 seconds, and shows excellent agreement with simulation prediction both in the stowed and deployed configurations.Comment: 12 pages, 12 figure