Theoretical studies of electronic structure and structural properties of anhydrous alkali metal oxalates: Part I. Electronic structure and electron density topology calculations

Author： Koleżyński A. Małecki A.

Publisher： Springer Publishing Company

ISSN： 1388-6150

Source： Journal of Thermal Analysis and Calorimetry, Vol.114, Iss.3, 2013-12, pp. : 1391-1399

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Abstract

The results of first principles calculations of band structure, density of states, and electron density topology of alkali metal oxalates are presented. The calculations have been carried out with WIEN2k ab initio program, using highly precise full potential linearized augmented plane wave method within density functional theory formalism. Calculated total electron density has been used in calculations of its topological properties (according to Bader’s quantum theory of atoms in molecules formalism) and Cioslowski and Mixon’s topological bond orders. The obtained results show important similarities between electronic structure and electron density topology for all analyzed structures with electronic structure close to Fermi energy typical for ionic compounds and bonding which is mainly covalent within the oxalate anion (with partly ionic character of carbon–oxygen bonds) and strongly ionic between oxalate anion and cationic sublattice. These results have been used as a basis for theoretical analysis of thermal decomposition process described in detail in part II of this paper (where also the results of additional calculations of atomic and bond valences, bond strengths and strains are presented).