The energy landscape concept and its implications for synthesis planning

Abstract

Synthesis of novel solids, in a chemical sense, is one of the spearheads of innovation in materials research. However, such an undertaking is substantially impaired by lack of control and predictability. We present a concept that points the way towards rational planning of syntheses in solid state and materials chemistry. The foundation of our approach is the representation of the whole material world, i.e., the known and not-yet-known chemical compounds, on an energy landscape, which implies information about the free energies of these configurations. From this it follows at once that all chemical compounds capable of existence (both thermodynamically stable and metastable ones) are already present in virtuo in this landscape. For the first step of synthesis planning, i.e., the identification of candidates that are capable of existence, we computationally search the respective potential energy landscapes for (meta)stable structure candidates. Recently we have extended our techniques to finite temperatures and pressures and calculated phase diagrams, including metastable manifestations of matter, without resorting to any experimental pre-information. The conception developed is physically consistent, and its feasibility has been proven. Applying appropriate experimental tools has enabled us to realize, e.g., elusive Na 3 N, including almost all of its predicted polymorphs, many years after the predictions were published.

Conceptual Inorganic Materials Discovery – A Road Map

“…The strategy for rendering solid materials synthesis rationally plannable is based on the “Energy Landscape Concept” of chemical matter . The starting point is the space containing all possible arrangements of atoms, the atomic configuration space.…”

“…The Energy Landscape Concept applies generally. Hence, it is also including the traditional heuristic or inductive approaches to synthesis planning, both conceptual and explorative ones, thus enabling a holistic view of chemistry . Conventionally, chemical energy landscapes have been explored by experiment, where each successful realization of a new compound would correspond to the discovery of a new minimum in the respective energy landscape.…”

“…Though energy evidently is the essential factor that determines the structure of the chemical energy landscape, mainly non‐physical tools have been utilized up to now to contrive goals for syntheses. These widely used approaches to conceiving yet unknown compositions and structures are commonly based on topological features known from experience to be stable, and all schemes used for systematizing crystal structures also have some predictive power, in principle . However, such empirical reasonings suffer from deficiencies, are lacking generality and predictive power, in particular.…”

“…The dilemma mentioned persists, even when one drops the objective of realizing a specific property, it is reflecting a kind of “trade mark” of solid state synthesis in general, which is its unpredictability. Because of the fundamental relevance of efficient solid materials synthesis, for science and technology, we have investigated and developed an approach to conceptual solid state synthesis . This progress report reviews these efforts up to the stage presently arrived at.…”

Theoretical and experimental study of high-pressure synthesized B20-type compounds Mn1− x (Co,Rh) x Ge

“…The design, fabrication and study of novel compounds not found in nature, with an emphasis on interrelation between their electronic structure and physico-chemical properties, provide a promising basis for the development of technologically important materials [1][2][3][4][5][6][7]. Examples of such systems are transition-metal (TM) monogermanides with a cubic B20-type crystal structure, which are attractive for researchers in view of their exotic properties and hence, a variety of possible applications.…”