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

Abstract

Here, we introduce a hybrid method, named Kick–Fukui, to explore the potential energy surface (PES) of clusters and molecules using the Coulombic integral between the Fukui functions in the first screening of the best individuals. In the process, small stable molecules or clusters whose combination has the stoichiometry of the explored species are used as assembly units. First, a small set of candidates has been selected from a large and stochastically generated (Kick) population according to the maximum value of the Coulombic integral between the Fukui functions of both fragments. Subsequently, these few candidates are optimized using a gradient method and density functional theory (DFT) calculations. The performance of the program has been evaluated to explore the PES of various systems, including atomic and molecular clusters. In most cases studied, the global minimum (GM) has been identified with a low computational cost. The strategy does not allow to identify the GM of some silicon clusters; however, it predicts local minima very close in energy to the GM that could be used as the initial population of evolutionary algorithms.

Molecular Interactions From the Density Functional Theory for Chemical Reactivity: The Interaction Energy Between Two-Reagents

“…This term plays a decisive role in the theory of Frontier-molecular orbital interactions put forth by Berkowitz ( Berkowitz, 1987 ) and it justifies the use of the Fukui potential as a fundamental reactivity indicator ( Cardenas et al, 2011b ; Cardenas, 2011 ; Osorio et al, 2011 ; Yañez et al, 2021 ). When only the potential is varied, but not the number of electrons, one obtains potential-based reactivity indicators ( Ayers and Parr, 2001 ; Cedillo et al, 2007 ; Ayers P. W. et al, 2009 ; Liu et al, 2009 ; Muñoz et al, 2020 ).…”

“…The Coulomb interaction between the Fukui functions ( Parr and Yang, 1984 ; Yang et al, 1984 ; Ayers and Levy, 2000 ; Ayers P. W. et al, 2009 ; Osorio et al, 2011 ; Yañez et al, 2021 ) is the leading-order purely electron-transfer term, …”

Molecular interactions from the density functional theory for chemical reactivity: Interaction chemical potential, hardness, and reactivity principles

“…The first term is likewise positive if that h AB < η B . This can always be ensured by taking the initial separation of reagents to be sufficiently large (Yañez et al, 2021). For instance, for Fukui functions localized on two atomic sites separated by 5 Å, h AB is less than 3 eV.…”

Can second-order perturbation theory accurately predict electron density of open-shell molecules? The importance of self-consistency

“…4 shows the 3D surfaces of errors relative to the CCSD reference of MP2 and OBMP2 results. Except for the Fukui function f + ( r ) of C and N, OBMP2 errors are much smaller than standard MP2 errors and nearly vanish for f + ( r ) of O and f − ( r ) of N. The Fukui functions and their generalization have been widely used to predict molecular structure, 41 we thus expect that OBMP2 will be an affordable and accurate approach to such an exciting topic.…”