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Molecules for materials: Germanium hydride neutrals and anions. Molecular structures, electron affinities, and thermochemistry of GeH n /GeH n − ( n = 0–4) and Ge 2 H n /Ge 2 H n − ( n = 0–6)
Author(s) -
Li QianShu,
Lü RuiHua,
Xie Yaoming,
Schaefer Henry F.
Publication year - 2002
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.10397
Subject(s) - thermochemistry , electron affinity (data page) , chemistry , germanium , adiabatic process , affinities , molecule , ion , hydride , germane , density functional theory , degenerate energy levels , computational chemistry , electron , crystallography , atomic physics , stereochemistry , physics , silicon , metal , thermodynamics , organic chemistry , quantum mechanics
The GeH n ( n = 0–4) and Ge 2 H n ( n = 0–6) systems have been studied systematically by five different density functional methods. The basis sets employed are of double‐ζ plus polarization quality with additional s‐ and p‐type diffuse functions, labeled DZP++. For each compound plausible energetically low‐lying structures were optimized. The methods used have been calibrated against a comprehensive tabulation of experimental electron affinities ( Chemical Reviews 102, 231, 2002). The geometries predicted in this work include yet unknown anionic species, such as Ge 2 H − , Ge 2 H 2 − , Ge 2 H 3 − , Ge 2 H 4 − , and Ge 2 H 5 − . In general, the BHLYP method predicts the geometries closest to the few available experimental structures. A number of structures rather different from the analogous well‐characterized hydrocarbon radicals and anions are predicted. For example, a vinylidene‐like GeGeH 2 −structure is the global minimum of Ge 2 H 2 − . For neutral Ge 2 H 4 , a methylcarbene‐like HGë‐GeH 3 is neally degenerate with the trans ‐bent H 2 GeGeH 2 structure. For the Ge 2 H 4 −anion, the methylcarbene‐like system is the global minimum. The three different neutral‐anion energy differences reported in this research are: the adiabatic electron affinity (EA ad ), the vertical electron affinity (EA vert ), and the vertical detachment energy (VDE). For this family of molecules the B3LYP method appears to predict the most reliable electron affinities. The adiabatic electron affinities after the ZPVE correction are predicted to be 2.02 (Ge 2 ), 2.05 (Ge 2 H), 1.25 (Ge 2 H 2 ), 2.09 (Ge 2 H 3 ), 1.71 (Ge 2 H 4 ), 2.17 (Ge 2 H 5 ), and −0.02 (Ge 2 H 6 ) eV. We also reported the dissociation energies for the GeH n ( n = 1–4) and Ge 2 H n ( n = 1–6) systems, as well as those for their anionic counterparts. Our theoretical predictions provide strong motivation for the further experimental study of these important germanium hydrides. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 1642–1655, 2002