The Crystal Orbital Hamilton Population (COHP) Method as a Tool to Visualize and Analyze Chemical Bonding in Intermetallic Compounds

Abstract

Abstract:Recognizing the bonding situations in chemical compounds is of fundamental interest for materials design because this very knowledge allows us to understand the sheer existence of a material and the structural arrangement of its constituting atoms. Since its definition 25 years ago, the Crystal Orbital Hamilton Population (COHP) method has been established as an efficient and reliable tool to extract the chemical-bonding information based on electronic-structure calculations of various quantum-chemical types. In this review, we present a brief introduction into the theoretical background of the COHP method and illustrate the latter by diverse applications, in particular by looking at representatives of the class of (polar) intermetallic compounds, usually considered as "black sheep" in the light of valence-electron counting schemes.

Revisiting the Zintl‒Klemm Concept for ALn2Ag3Te5-Type Alkaline-Metal (A) Lanthanide (Ln) Silver Tellurides

“…This circumstance becomes even clearer from a bonding analysis that has been accomplished based on the projected crystal orbital Hamilton populations (−pCOHP) and their respective integrated values (−IpCOHP; Figure 4). In addition, the cumulative −IpCOHP/cell values, i.e., the sum of all −IpCOHP/bond values for a particular sort of interatomic interaction, were projected as percentages of the net bonding capacity-a procedure [30] that has been largely employed to evaluate the roles of different interactions in a given solid-state material. (32) is nearly similar to those of the Ag−Te (48) and Ce−Te (48), the latter interactions correspond to much higher −IpCOHP/bond values, and hence higher percentages, than the Cs−Te interactions.…”

“…The nature of bonding in CsCe 2 Ag 3 Te 5 was determined based on the projected crystal orbital Hamilton populations (pCOHP) [48], and Mulliken as well as Löwdin population analysis. In the former approach, which is a variant of the COHP technique [30,49], the off-site DOS are weighted with the respective Hamiltonian matrix elements to reveal bonding, non-bonding, and antibonding interactions. The Mulliken and Löwdin charges are obtained by subtracting the gross population of a given type of atom from its number of valence-electrons [21].…”

Revealing the Nature of Chemical Bonding in an ALn2Ag3Te5-Type Alkaline-Metal (A) Lanthanide (Ln) Silver Telluride

“…To provide an insight into the bonding situation in RbPr2Ag3Te5, we followed up with an examination of the crystal orbital Hamilton population curves (COHP; Figure 2) and their respective integrated values (Table 3). In this context, the cumulative -ICOHP/cell values, i.e., the sums of the negative ICOHP/bond values of all nearest neighboring contacts within one unit cell, were projected as percentages of the net bonding capabilities for each sort of interaction to identify roles of the diverse interactions in overall bonding-a procedure that has been largely employed elsewhere [21,22,[33][34][35][36]. (Figure 2) reveals that the occupied states close to the Fermi level, E F , originate to a large extent from the Ag-d and Te-p atomic orbitals beside minor contributions from the Pr-d states.…”

“…A chemical bonding analysis of RbPr 2 Ag 3 Te 5 was accomplished based on the crystal orbital Hamilton population (COHP [36,58]) method, in which the off-site projected DOS are weighted with the respective Hamilton matrix elements to identify bonding, non-bonding, and antibonding interactions. The COHP curves and the corresponding integrated values (ICOHP) were computed utilizing the tight-binding linear-muffin-tin orbital (TB-LMTO) method in the atomic sphere approximation (ASA) [59][60][61] and employing the von Barth-Hedin [62] exchange-correlation functional.…”

Chemical Bonding and Physical Properties in Quasicrystals and Their Related Approximant Phases: Known Facts and Current Perspectives

“…Accordingly, the precise relationship between the Fermi-surface-Brillouin-zone mechanism, sp-d hybridization, and covalent bonding formation should be further clarified in order to gain a proper understanding of the bond nature in QCs [106]. In this regard, the visualization of the bonding nature in terms of the crystal orbital Hamilton population will be a very convenient tool [107,108].…”