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Title: Multireference Ab Initio Study of Ligand Field d–d Transitions in Octahedral Transition-Metal Oxide Clusters

Authors:
 [1];  [1];  [1]
  1. Argonne−Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Argonne-Northwestern Solar Energy Research Center (ANSER)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1384726
DOE Contract Number:
SC0001059
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 118; Journal Issue: 50; Related Information: ANSER partners with Northwestern University (lead); Argonne National Laboratory; University of Chicago; University of Illinois, Urbana-Champaign; Yale University
Country of Publication:
United States
Language:
English
Subject:
catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis (natural and artificial), bio-inspired, hydrogen and fuel cells, electrodes - solar, defects, charge transport, spin dynamics, membrane, materials and chemistry by design, optics, synthesis (novel materials), synthesis (self-assembly)

Citation Formats

Yang, Yang, Ratner, Mark A., and Schatz, George C. Multireference Ab Initio Study of Ligand Field d–d Transitions in Octahedral Transition-Metal Oxide Clusters. United States: N. p., 2014. Web. doi:10.1021/jp5052672.
Yang, Yang, Ratner, Mark A., & Schatz, George C. Multireference Ab Initio Study of Ligand Field d–d Transitions in Octahedral Transition-Metal Oxide Clusters. United States. doi:10.1021/jp5052672.
Yang, Yang, Ratner, Mark A., and Schatz, George C. Tue . "Multireference Ab Initio Study of Ligand Field d–d Transitions in Octahedral Transition-Metal Oxide Clusters". United States. doi:10.1021/jp5052672.
@article{osti_1384726,
title = {Multireference Ab Initio Study of Ligand Field d–d Transitions in Octahedral Transition-Metal Oxide Clusters},
author = {Yang, Yang and Ratner, Mark A. and Schatz, George C.},
abstractNote = {},
doi = {10.1021/jp5052672},
journal = {Journal of Physical Chemistry. C},
number = 50,
volume = 118,
place = {United States},
year = {Tue Jul 15 00:00:00 EDT 2014},
month = {Tue Jul 15 00:00:00 EDT 2014}
}
  • We report Car-Parrinello molecular dynamics simulations of the oxidation of ligand-protected aluminum clusters that form a prototypical cluster-assembled material. These clusters contain a small aluminum core surrounded by a monolayer of organic ligand. The aromatic cyclopentadienyl ligands form a strong bond with surface Al atoms, giving rise to an organometallic cluster that crystallizes into a low-symmetry solid and is briefly stable in air before oxidizing. Our calculations of isolated aluminum/cyclopentadienyl clusters reacting with oxygen show minimal reaction between the ligand and O{sub 2} molecules at simulation temperatures of 500 and 1000 K. In all cases, the reaction pathway involves O{submore » 2} diffusing through the ligand barrier, splitting into atomic oxygen upon contact with the aluminum, and forming an oxide cluster with aluminum/ligand bonds still largely intact. Loss of individual aluminum-ligand units, as expected from unimolecular decomposition calculations, is not observed except following significant oxidation. These calculations highlight the role of the ligand in providing a steric barrier against oxidizers and in maintaining the large aluminum surface area of the solid-state cluster material.« less
  • An {ital ab initio} Hartree{endash}Fock molecular dynamics procedure is applied to study structural and dynamical properties of Li{sub 9}{sup +}, Li{sub 10}, and Li{sub 11}{sup +} clusters with eight and ten valence electrons, corresponding to {open_quotes}closed{close_quotes} and {open_quotes}open{close_quotes} shell systems. Gradients of the ground state energy are used to compute the forces acting on atoms at each geometric configuration along trajectories generated by solving classical equations of motion. Dynamics of different isomers for each cluster size have been investigated as a function of excess energy. It is shown that different isomers, even those similar in energy, can exhibit different structuralmore » and dynamical behavior. The analysis of the simulations leads to the conclusion that structures with a central atom, in particular the centered antiprism of Li{sub 9}{sup +}, exhibit concerted mobility of the peripheral atoms at relatively low excess energy. In contrast, compact tetrahedral type structures show much more rigid behavior at low excess energy. However, the former ones need larger excess of internal energy to undergo isomerizations to geometrically different structures than the latter ones, at least in the case of Li{sub 9}{sup +} and Li{sub 11}{sup +} clusters. At the time scale of our simulations we found that for the intermediate excess energies it is {open_quotes}easier{close_quotes} to carry the cluster in the basin of the lowest energy isomer than in the reverse direction. Moreover, for different cluster sizes isomerization processes occur at different excess energies (temperatures), which is a consequence of the differences in the structural properties rather than in the number of the valence electrons. It has been found that the liquidlike behavior in small Li clusters becomes apparent at relatively high temperature in spite of large mobility of their atoms. {copyright} {ital 1997 American Institute of Physics.}« less
  • No abstract prepared.
  • The authors present optimized geometries and binding energies for alkali metal cation complexes with anisole (methoxybenzene). Results are obtained for Li{sup +} through Cs{sup +} at the RHF/6-311G* and MP2/6-311+G* levels of theory, with K{sup +}, Rb{sup +}, and Cs{sup +} represented by relativistic ECPs and associated valence basis sets. RHF/6-311G{sup {minus}} frequencies are used to verify that the optimized geometries are minima and to calculate binding enthalpies. The effects of basis set superposition error (BSSE) are estimated at both the RHF and MP2 levels. The alkali metals bind to anisole in two ways, either predominantly through interactions with themore » aromatic ring or with the ether oxygen. For binding to the ring, BSSE-corrected MP2/6-311+G* binding enthalpies (in kcal/mol) of {minus}38.1 (Li{sup +}), {minus}23.6 (Na{sup +}), {minus}18.3 (K{sup +}), {minus}15.4 (Rb{sup +}), and {minus}13.6 (Cs{sup +}) were obtained. The average distances (in {angstrom}) between the ring carbons and the cations are 2.33 (Li{sup +}), 2.79 (Na{sup +}), 3.20 (K{sup +}), 3.44 (Rb{sup +}), and 3.70 (Cs{sup +}). For binding to the ether oxygen, the BSSE-corrected MP2/6-311+G* binding enthalpies (in kcal/mol) are {minus}37.6 (Li{sup +}), {minus}25.2 (Na{sup +}), {minus}19.4 (K{sup +}), {minus}16.4 (Rb{sup +}), and {minus}14.3 (Cs{sup +}). The distances (in {angstrom}) between the ether oxygen and the cations are 1.82 (Li{sup +}), 2.24 (Na{sup +}), 2.62 (K{sup +}), 2.87 (Rb{sup +}), and 3.10 (Cs{sup +}). Although the differences in binding energy between the two sites are small, the cations generally prefer to bind to the oxygen.« less