Energy landscapes in inorganic chemistry

Structure prediction in low dimensions: concepts, issues and examples

“…This set of structure candidates is often supplemented by structures that are analogues to structures found in chemically related systems that have been directly extracted from a database [40][41][42][43] or generated by an analogy-based algorithm such as a neural network. An overview of some of the most popular algorithms can be found in the literature [38,44].…”

“…Quite generally, the prediction of structure modifications for low-dimensional chemical systems and of those for finite or infinite three-dimensional systems such as clusters and molecules or crystals follows the same general approach [ 38 ]. A useful polymorph is characterized by corresponding to a locally ergodic region on the energy landscape of the system, i.e.…”

“…the many homotops of an alloy cluster or the many configurations in a solid solution that contribute to its configurational entropy. Here, we also note that entropic aspects are not only relevant for the computation of the local free energy but also play an important role as entropic barriers that help stabilize the region complementing the more familiar energetic barriers [ 38 , 39 ]. As a consequence, the global search algorithms also need to incorporate means to overcome not only energetic barriers but also entropic ones, which are not always amenable to, e.g.…”

“…By contrast, due to the essentially infinitely large number of atoms in a bulk material, one cannot represent the complete system in the computer, and one is forced to use rather drastic approximations when searching for structure candidates with only finite computational resources. As discussed in [ 38 ], the most commonly used approach is to employ a so-called periodic approximant for the bulk system, i.e. we define the model for the system via the variable cell parameters of a periodic unit cell that contains a finite number of formula units of the system.…”

Ab initio computation of low-temperature miscibility gap of V(Se,Te)2

“…To address this question, it is necessary to compute the phase diagram of the system, including the possibility of solid solution phases, for a (not-yet synthesized) TMD layer. In the present study, we have used a general methodology [53][54][55] to determine feasible low-energy ordered atom configurations of a monolayer of the 2H phase of V(Se,Te) 2 , including the possible presence of solid solution phases, as a function of composition, followed by the construction of the composition-temperature phase diagram. For comparison, these calculations were also performed for the analogous bulk structure.…”