Density Functional Theory Study On Isomeric Stability Of Fullerenes,kinetic Energy Density And Strong Interaction

The basic theorem of density functional theory?DFT?reveals that the information contained in electron density should be sufficient to accurately determine any properties of the ground state,including reactivity and various physical and chemical properties.Density functional reactivity theory?DFRT?is to describe the properties and reactivity of the system using only electron density and related physical quantities.In this work,DFRT is used to explore the origin and nature of isomeric stability of fullerene;The Pauli exclusion principle directly measures the contribution of kinetic energy,it is used to effectively evaluate quality of kinetic energy density?KED?;Using Pauli energy to define the strong covalent interaction?SCI?index,we explored strong interaction between heavy-metal dimers.?1?In this work,DFT and information-theoretic approach in DFRT are used to explore determinants of the stability of fullerene isomers.The total energy decomposition analysis is beneficial to understand the origin and nature of isomeric stability.Our results showcase that the electrostatic potential is the dominant factor contributing to the isomeric stability of these fullerenes,and other contributions such as steric and quantum effects play minor but indispensable roles.This study also finds that the origin of the isomeric stability of these species is due to the spatial delocalization of the electron density.The work provides novel insights into the isomeric stability of fullerene molecules.?2?In KED system,a total of 22 approximate semilocal noninteracting KED functionals are tested for 18 neutral atoms and 20 small molecules from the literature.The results show that generalized gradient approximation?GGA?formulas of the KED functional can often reasonably accurately predict the total kinetic energy value for atoms and molecules but failed miserably to forecast the integrated values for Pauli energy related properties.The reason behind this is that presently available approximate KED functionals are unable to accurately account for the kinetic energy distribution in the bonding range away from nuclei,where the Pauli energy plays a crucial role.Our results strongly suggest that the key information missing in approximate KED functionals comes from the medium binding regions,not nuclear cusps nor asymptotic areas,and the Pauli energy is a reliable measure of the quality of approximate KED functionals.Future efforts in developing better KED approximations should be invested in the regions of molecules where chemical bonds are formed in order to accurately account for the Pauli energy.?3?Strong covalent interaction?SCI?is a covalent bond in which two or more strong covalent interaction by means of using SCI index and its isosurface shapes.Previous work has proven that its close relationship with the electron localization function?ELF?was elucidated,and their isosurface shape can describe the multiple bond order.In addition,the strong interaction between heavy metal atoms can be verified by combining Pipek-Mezey localized molecular orbitals?LMOs?method and Mayer bond order before orbital occupancy-perturbation.The results show that there are multiple covalent orders between dimers of heavy-metals such as Cr₂,Mo₂,and W₂,various ligands present in the bimetal complexes support the formation of different types of bond order.This work provides a robust evidence to determine covalent bond orders for strong interactions in complex systems,pinpointing the physiochemical origin of strong interactions.These tools should be able to be applied to other systems in different fields to effectively appreciate strong covalent interactions.