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Effect of Li Adsorption on the Electronic and Hydrogen Storage Properties of Acenes: A Dispersion-Corrected TAO-DFT Study

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ABSTRACT

Due to the presence of strong static correlation effects and noncovalent interactions, accurate prediction of the electronic and hydrogen storage properties of Li-adsorbed acenes with n linearly fused benzene rings (n = 3–8) has been very challenging for conventional electronic structure methods. To meet the challenge, we study these properties using our recently developed thermally-assisted-occupation density functional theory (TAO-DFT) with dispersion corrections. In contrast to pure acenes, the binding energies of H2 molecules on Li-adsorbed acenes are in the ideal binding energy range (about 20 to 40 kJ/mol per H2). Besides, the H2 gravimetric storage capacities of Li-adsorbed acenes are in the range of 9.9 to 10.7 wt%, satisfying the United States Department of Energy (USDOE) ultimate target of 7.5 wt%. On the basis of our results, Li-adsorbed acenes can be high-capacity hydrogen storage materials for reversible hydrogen uptake and release at ambient conditions.

No MeSH data available.


Symmetrized von Neumann entropy for the lowest singlet state of pure/Li-adsorbed n-acene as a function of the chain length, calculated using TAO-BLYP-D.
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f7: Symmetrized von Neumann entropy for the lowest singlet state of pure/Li-adsorbed n-acene as a function of the chain length, calculated using TAO-BLYP-D.

Mentions: for the lowest singlet state of pure/Li-adsorbed n-acene as a function of the chain length. Here, fi the occupation number of the ith orbital obtained with TAO-BLYP-D, ranging from 0 to 1, is approximately equal to the occupation number of the ith natural orbital3538. Note that SvN provides insignificant contributions for a single-reference system ({fi} are close to either 0 or 1), and rapidly increases with the number of active orbitals ({fi} are fractional for active orbitals, and are close to either 0 or 1 for others). As shown in Fig. 7, SvN monotonically increases with the chain length. Therefore, the multi-reference character of pure/Li-adsorbed n-acene increases with the chain length.


Effect of Li Adsorption on the Electronic and Hydrogen Storage Properties of Acenes: A Dispersion-Corrected TAO-DFT Study
Symmetrized von Neumann entropy for the lowest singlet state of pure/Li-adsorbed n-acene as a function of the chain length, calculated using TAO-BLYP-D.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016802&req=5

f7: Symmetrized von Neumann entropy for the lowest singlet state of pure/Li-adsorbed n-acene as a function of the chain length, calculated using TAO-BLYP-D.
Mentions: for the lowest singlet state of pure/Li-adsorbed n-acene as a function of the chain length. Here, fi the occupation number of the ith orbital obtained with TAO-BLYP-D, ranging from 0 to 1, is approximately equal to the occupation number of the ith natural orbital3538. Note that SvN provides insignificant contributions for a single-reference system ({fi} are close to either 0 or 1), and rapidly increases with the number of active orbitals ({fi} are fractional for active orbitals, and are close to either 0 or 1 for others). As shown in Fig. 7, SvN monotonically increases with the chain length. Therefore, the multi-reference character of pure/Li-adsorbed n-acene increases with the chain length.

View Article: PubMed Central - PubMed

ABSTRACT

Due to the presence of strong static correlation effects and noncovalent interactions, accurate prediction of the electronic and hydrogen storage properties of Li-adsorbed acenes with n linearly fused benzene rings (n = 3–8) has been very challenging for conventional electronic structure methods. To meet the challenge, we study these properties using our recently developed thermally-assisted-occupation density functional theory (TAO-DFT) with dispersion corrections. In contrast to pure acenes, the binding energies of H2 molecules on Li-adsorbed acenes are in the ideal binding energy range (about 20 to 40 kJ/mol per H2). Besides, the H2 gravimetric storage capacities of Li-adsorbed acenes are in the range of 9.9 to 10.7 wt%, satisfying the United States Department of Energy (USDOE) ultimate target of 7.5 wt%. On the basis of our results, Li-adsorbed acenes can be high-capacity hydrogen storage materials for reversible hydrogen uptake and release at ambient conditions.

No MeSH data available.