A Fukui function‐guided genetic algorithm. Assessment on structural prediction of Si_n (n = 12–20) clusters

Abstract

Theoretical studies are essential for the structural characterization of clusters, when it comes to rationalize their unique size-dependent properties and composition. However, the rapid growth of local minima on the potential energy surface (PES), with respect to cluster size, makes the candidate identification a challenging undertaking. In this article, we introduce a hybrid strategy to explore the PES of clusters. This proposal involves the use of a biased initial population of a genetic algorithm procedure. Each individual in this population is built by assembling small fragments, according to the best matching of the Fukui function. The performance of a genetic algorithm procedure. The performance of the method is assessed on the PES exploration of medium-sized Si clusters (n = 12-20). The most relevant results are: (a) the method converges at almost half of the time used by the canonical version of the GA and, (b) in all the studied cases, with the exception of Si and Si , the method allowed to identify the global minimum (GM) and other important low-lying structures. Additionally, the apparent deficiency of the proposal to identify the GM was corrected when a Si atom, or other low-lying isomers, were considered to build the clusters. © 2017 Wiley Periodicals, Inc.

New insights in chemical reactivity from quantum chemical topology

“…However, as recalled recently by Geerling et al, most cDFT studies have focused on interpreting the experimental or computational results of a reaction, and less on the prediction of unknown products 19 . Indeed, to our knowledge, only a handful of studies have used these indices semi‐quantitatively to predict the most stable products of a reaction 20,21 …”

“…[19] Indeed, to our knowledge, only a handful of studies have used these indices semiquantitatively to predict the most stable products of a reaction. [20,21] Meanwhile, alternative strategies of bonding analysis belonging to the Quantum Chemical Topology (QCT) methodology [22][23][24][25][26] have been developed for a long time in the field of non-relativistic quantum calculations. These approaches grew up from the pioneering works of Richard F. W. Bader and coworkers in the 70s which was initially motived by the generalization of the quantum mechanical principle of stationary action to a molecular subsystem.…”

Kick–Fukui: A Fukui Function-Guided Method for Molecular Structure Prediction

“…To accelerate the algorithm, we have resorted to condensed values of the FF, which allow eq to be reduced to a discrete sum, where f k – is the condensed value of f r – in a volume k (similarly, f k ′ + is obtained). It should be noted that in the past some of the current authors used this approach in a qualitative way to explore silicon cluster structures. , Additionally, Grillo et al recently used an analogue equation to explore the PES of enzymatic reactions . In general, the FF is condensed using atomic charge analysis centered on atoms. − Some of us, however, have proposed to condense the FF in its basins, as we can see in Figure .…”

“…Then, the descriptor J f (eq ) is used to identify the best conformations, subsequently optimized using a gradient method and DFT computations. To assess the methodology, we search for the lowest-energy structures of a broad range of chemical species, including molecular, − atomic, ,, and ligand-stabilized Zintl-type clusters . Satisfactorily, we have identified the GM reported in the literature in all of the cases studied with a few exceptions. ,− These results encourage us to envisage this proposal as the first step, in an alternative direction, toward using CDFT as a source of predictive tools to help in molecular design.…”

“…To assess the methodology, we search for the lowest-energy structures of a broad range of chemical species, including molecular, − atomic, ,, and ligand-stabilized Zintl-type clusters . Satisfactorily, we have identified the GM reported in the literature in all of the cases studied with a few exceptions. ,− These results encourage us to envisage this proposal as the first step, in an alternative direction, toward using CDFT as a source of predictive tools to help in molecular design. In addition, recent studies are revitalizing the use of CDFT descriptors to guide PES exploration.…”