Beryllium and Magnesium Metal Clusters: New Globally Stable Structures and G₀W₀ Calculations

Abstract

We study the structural and electronic properties of beryllium (Be) and magnesium (Mg) clusters for sizes 2–20 using a two-step approach. In the first step, a global search of the stable and low-lying metastable isomer structures is carried out on the basis of first-principles potential energy surfaces at the level of the generalized gradient approximation (GGA) of density functional theory (DFT). In the second step, vertical ionization potentials (VIPs) and energy gaps between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are determined using the G 0 W 0 methods for up to the fourth-lowest-energy isomers. Novel globally lowest-energy isomer structures are identified for Be14, Mg14, and Mg16 clusters. The van der Waals interactions are found to have a stronger influence on Mg clusters than on Be clusters. A second-difference analysis for both the binding energies and HOMO–LUMO gaps reveals a close relationship between the structural stability and chemical hardness for both types of clusters.

Assessing the G0W0Γ0(1) Approach: Beyond G0W0 with Hedin’s Full Second-Order Self-Energy Contribution

“…GW emerges naturally from Hedin’s equations as the first-order approximation for the electron self-energy. Since its first applications to real materials in the 1980s, , the GW approximation has become the method of choice for band structure calculations of solids. − More recently, it has also gained attention in chemistry and applications to molecules and clusters are on the rise. − …”

Conceptual density functional theory based electronic structure principles

“… 235 Recently, a similar approach has been adopted in explaining the stability of metal clusters. 236 …”

Renormalized Singles Green's Function in the T-Matrix Approximation for Accurate Quasiparticle Energy Calculation

“…The GW method, [1][2][3] which is developed from Hedin's equations, 4 is a stateof-art formalism to study QP energies, and charged electronic excitations in molecules [5][6][7][8][9][10][11][12] and solids. [13][14][15][16][17][18][19][20][21] The success of the GW method stems from a clear physical interpretation for QP energies, a favorable computational scaling with respect to the size of systems and a proper description of the screened interaction. 1 The GW method is viewed as the "gold standard" for band gap calculations 22 for periodic systems, and the GW method has been widely used to investigate both valence [23][24][25] and core [26][27][28] state properties for molecular systems.…”