Comparative theoretical study of the electron affinities of the alkaline‐earth clusters: Be_n, Mg_n, and Ca_n (n = 2, 3)

Abstract

ABSTRACT:If in atoms only one type of the electron affinity (EA) can be defined, in molecules there are three types of EAs: the vertical electron affinity (VEA), adiabatic electron affinity (AEA), and vertical electron detachment energy (VEDE). These three types of EAs for beryllium, magnesium, and calcium dimers and trimers are calculated at the allelectron MP4(SDTQ) level employing the Dunning-type basis sets. All obtained EAs satisfy the following inequality VEDE Ͼ AEA Ͼ VEA and are quite large to be observed in experiment, especially in the trimer case: VEDE (Be 3 Ϫ ) ϭ 1.63 eV, VEDE (Mg 3 Ϫ ) ϭ 0.72 eV, and VEDE (Ca 3 Ϫ ) ϭ 0.95 eV. The decomposition of VEDE into physical components (Koopmans, relaxation, and correlation) and the atomic orbital population analysis (at the NBO level) are used to elucidate the nature of the outer electron binding in studied anions.

Neoadjuvant chemotherapy/gefitinib followed by concurrent chemotherapy/radiation therapy/gefitinib for patients with locally advanced squamous carcinoma of the head and neck

“…[198, 199] Although this field is new for him, his studies are carried out at the state‐of‐the‐art level. [19, 202, 203]…”

Geometries, Binding Energies, Ionization Potentials, and Electron Affinities of Metal Clusters: Mgn0, ± 1, n = 1–7

“…Theoretical investigations of magnesium clusters reported to date involve numerous Kohn–Sham density functional theory (DFT) calculations exploiting various exchange-correlation (XC) functionals ,,,,− and several ab initio wave function computations using Hartree–Fock theory, Møller–Plesset (MP) perturbation theory, including the second-order MP2 − and fourth-order MP4 treatments, ,, complete-active-space self-consistent-field (CASSCF) approach, , the coupled-cluster (CC) method , using a popular quasiperturbative CCSD­(T) , approximation, ,,,,, and the multireference configuration interaction (MRCI) method . A van der Waals potential for Mg 2 , in which damped dispersion contributions based on C 6 , C 8 , and C 10 coefficients were added to a repulsive potential based on Hartree–Fock calculations, has been reported as well …”

“…Understanding the dependence of structural, electronic, energetic, optical, and magnetic properties of atomic and molecular clusters on the system size is one of the most important aspects of cluster science. − This, in particular, applies to clusters formed by divalent metals, which have been of fundamental interest for quite some time. − In this category, clusters of magnesium atoms, which have an s 2 valence electron configuration, are especially interesting, since the smallest Mg cluster, namely Mg 2 , is a system characterized by the very weak binding of the van der Waals type governed by a delicate balance of dispersion and exchange repulsion forces, , which cannot be captured by the Hartree–Fock or other low-order theory treatments, whereas larger Mg n species are covalently bound and characterized by an increase in the degree of s-p hybridization with the number of atoms in the cluster, while having significant contributions from pairwise nonadditive many-body interactions. − Furthermore, one observes an unusually large and not always monotonic variation of bonding properties when going from the smaller magnesium clusters toward the larger ones and the bulk limit, and this nonmonotonic trend constitutes a challenge for electronic structure methods. Another challenge is the rapidly varying cohesive energy per atom in the smaller Mg n species; it is about 4 and 10 times larger in the Mg 3 and Mg 4 clusters than in Mg 2 .…”

Combinatorial Screening of Highly Active Pd Binary Catalysts for Electrochemical Oxygen Reduction

“…As the simplest model system for the alloy surfaces, here we use a trimer model. The trimer model has been used to study the formation of larger clusters and to understand the behavior of metals, such as electronic states, spin–orbit coupling, and intricate d-orbital bonding. − Of course, more sophisticated models would be needed for quantitative absolute energetics, but the primary purpose of using trimers in this study is to obtain the correct relative trends qualitatively. As we will show in the Results section, this simple trimer model reproduces the experimental trend quite well.…”