Theoretical studies on the bonding and thermodynamic properties of GenSim (m+n = 5) clusters: The precursors of germanium/silicon nanomaterials

Wielgus, Pawel; Roszak, Szczepan; Majumdar, D.; Saloni, Julia; Leszczynski, Jerzy

doi:doi:10.1063/1.2890038

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Potential energy curve for isomerization of N₂H₂ and C₂H₄ using the improved virtual orbital multireference Møller–Plesset perturbation theory

Multireference Møller–Plesset (MRMP) perturbation theory [ K. Hirao, Chem. Phys. Lett. 190, 374 (1992) ] is modified to use improved virtual orbitals (IVOs) and is applied to study ground state potential energy curves for isomerization and dissociation of the N2H2 and C2H4 molecules. In contrast to traditional MRMP or multistate multiconfiguration quasidegenerate perturbation theory where the reference functions are obtained from (often difficult to converge) state averaged multiconfiguration s...

Observation of the 5p Rydberg states of sulfur difluoride radical by resonance-enhanced multiphoton ionization spectroscopy

Sulfur difluoride radicals in their ground state have been produced by a “laser-free” pulsed dc discharge of the SF6/Ar gas mixtures in a supersonic molecular beam and detected by mass-selective resonance-enhanced multilphoton ionization (REMPI) spectroscopy in the wavelength range of 408–420 nm. Analyses of the (3+1) REMPI excitation spectrum have enabled identification of three hitherto unknown Rydberg states of this radical. Following the Rydberg state labeling in our previous work [ see J. ...

Theoretical studies on the Ge_nSi_m clusters have been carried out using advanced ab initio approaches. The lowest energy isomers were determined for the clusters with compositions n+m = 2–5. All possible isomers arising due to permutations of Ge and Si atoms were investigated. The L-shaped structure for the trimers, tetragonal with diagonal bond for tetramers, and a trigonal bipyramid for pentamers represent the energy optimized ground state geometries. The bonding analyses revealed that the trimers and tetramers are stabilized through multicenter π bonding. In pentamers, this stabilizing factor is eliminated due to the further cluster growth. The ionization of clusters does not change their geometrical characteristics. The agreement of the calculated ionization and atomization energies with those obtained from the mass spectrometric studies (through estimated appearance potential) validated the reported structures of the clusters. The bonding properties of these species are discussed using their molecular orbital characteristics and analysis of natural bond orbital population data.

Article Outline

INTRODUCTION
THEORETICAL APPROACH AND COMPUTATIONAL DETAILS
MOLECULAR STRUCTURES OF Ge_mSi_n CLUSTERS
1. The dimer (GeSi)
2. The trimers ( GeSi₂ and Ge₂Si )
3. Four-atom clusters ( GeSi₃ , Ge₂Si₂ , and Ge₃Si )
4. Five-atom clusters ( GeSi₄ , Ge₂Si₃ , Ge₃Si₂ , and Ge₄Si )
THERMODYNAMICS
CONCLUSIONS

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KEYWORDS and PACS

Keywords

ab initio calculations, atomic clusters, bonds (chemical), dissociation energies, germanium, ground states, ionisation, mass spectra, nanostructured materials, orbital calculations, silicon, thermodynamic properties

PACS

61.46.Bc

Structure of clusters (e.g., metcars; not fragments of crystals; free or loosely aggregated or loosely attached to a substrate)
65.80.-g

Thermal properties of small particles, nanocrystals, nanotubes, and other related systems
73.22.-f

Electronic structure of nanoscale materials and related systems
71.15.-m

Methods of electronic structure calculations

ARTICLE DATA

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http://dx.doi.org/10.1063/1.2890038

PUBLICATION DATA

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0021-9606 (print)

1089-7690 (online)

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American Institute of Physics

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