The Journal of Chemical Physics 160 (2023): 152501

doi: 10.1063/5.0199247

Stretching or compression can induce significant energetic, geometric, and spectroscopic changes in materials. To fully exploit these effects in the design of mechano- or piezo-chromic materials, self-healing polymers, and other mechanoresponsive devices, a detailed knowledge about the distribution of mechanical strain in the material is essential. Within the past decade, Judgement of Energy DIstribution (JEDI) analysis has emerged as a useful tool for this purpose. Based on the harmonic approximation, the strain energy in each bond length, bond angle, and dihedral angle of the deformed system is calculated using quantum chemical methods. This allows the identification of the force-bearing scaffold of the system, leading to an understanding of mechanochemical processes at the most fundamental level. Here, we present a publicly available code that generalizes the JEDI analysis, which has previously only been available for isolated molecules. Now, the code has been extended to two- and three-dimensional periodic systems, supramolecular clusters, and substructures of chemical systems under various types of deformation. Due to the implementation of JEDI into the Atomic Simulation Environment, the JEDI analysis can be interfaced with a plethora of program packages that allow the calculation of electronic energies for molecular systems and systems with periodic boundary conditions. The automated generation of a color-coded three-dimensional structure via the Visual Molecular Dynamics program allows insightful visual analyses of the force-bearing scaffold of the strained system.

© 2024 Author(s). Published under an exclusive license by AIP Publishing.

Theoretical and Computational Chemistry (2023) 

doi: 10.26434/chemrxiv-2023-nr314

The field of liquid-phase and solid-state high-pressure chemistry has exploded since the advent of the diamond anvil cell, an experimental technique that allows the application of pressures up to several hundred gigapascal. To complement high-pressure experiments, a large number of computational tools have been developed. These techniques enable the simulation of chemical systems, their sizes ranging from single atoms to infinitely large crystals, under high pressure and the calculation of the resulting structural, electronic and spectroscopic changes. At the most fundamental level, computational methods using carefully tailored wall potentials allow the analytical calculation of energies and electronic properties of compressed atoms. Molecules and molecular clusters can be compressed either via mechanochemical approaches or via more sophisticated computational protocols using implicit or explicit solvation approaches, typically in combination with Density Functional Theory, thus allowing the simulation of pressure-induced chemical reactions. Crystals and other periodic systems can be routinely simulated under pressure as well, both in a static and in a dynamic manner, to predict the changes of crystallographic data under pressure and high-pressure crystal structure transitions. In this review, the theoretical foundations of the available computational tools for simulating high-pressure chemistry are introduced and example applications demonstrating the strengths and weaknesses of each approach are discussed.

© 2024, The Authors, CC BY 4.0

44th COSPAR Scientific Assembly. Held 16-24 July, 2022. Online at https://www.cosparathens2022.org/. Abstract PEX.2-0002-22.

Bibcode: 2022cosp...44.3186A

Leading space agencies have the intention to bring humans to Mars in the next decades, and some private companies push for sooner deadlines. In fact, promises and plans to land humans on Mars have recurrently been announced since the end of the Apollo era, but have remained largely incomplete or even abandoned. At the University of Bremen, we are convinced that human Mars exploration will happen and that it will have a huge impact on both humankind and on the Martian environment. Given that even optimists do not see humans on Mars before the 2030s, we believe that now is the right moment to research possible scenarios for human Mars exploration and settlement, and to study the consequences for Earth, Mars and humankind. To this end, we have formed a new research initiative "Humans on Mars - Pathways to a long-term sustainable human presence" at the University of Bremen. Our approach to human Mars exploration is transdisciplinary and human-centered. On one hand, humankind has experienced tremendous progress and increase in welfare since the Apollo era. On the other hand, we see unambiguously the immense impact of increasing population and welfare on the environmental pollution and associated climate changes. In a nutshell, while the development of new technologies has been the main driver of progress, it has also put Earth in danger. We here argue that human Mars exploration can be instrumental in leading a change from a technology-centered toward a human-centered society, thereby solving our most pressing problems on Earth. Specifically, the thin CO2 Martian atmosphere, the scarcity of energy sources and water, the difficulties to produce food and consumables, and the need for cooperative human-robotic crews, pose challenges whose solutions will enormously benefit Earth. In short, the mindset emerging from thinking under the severe constraints on Mars could be the key to making our presence on Earth sustainable. In this talk, we will present our vision and report on the progress made in selected areas, starting with the shifts in experience and demands on new ways of interaction which come with humankind's expansion to Mars. These include the interactions of the humans on Mars with the humans on Earth on one hand and their habitat and swarm of robots on the other. We will present our efforts in in-situ resource utilization, which focus on sustainable bioproduction, the extraterrestrial fabrication of metal alloys, the production with impure materials and the harvesting of energy from space radiation.