Quantum Monte Carlo Calculations of Dihydrogen Binding Energetics on Ca Cations: an Assessment of Errors in Density Functionals for Weakly Bonded Systems - Condensed Matter > Materials ScienceReport as inadecuate




Quantum Monte Carlo Calculations of Dihydrogen Binding Energetics on Ca Cations: an Assessment of Errors in Density Functionals for Weakly Bonded Systems - Condensed Matter > Materials Science - Download this document for free, or read online. Document in PDF available to download.

Abstract: We investigate the binding of single and quadruple hydrogen molecules on apositively charged Ca ion. By comparing with benchmark quantum Monte CarloQMC calculations we demonstrate wide variability in other more approximateelectronic structure methods including common density functionals. Singledeterminant QMC calculations find no binding at short range by approximately0.1 eV for the quadruple hydrogen molecule case, for a fixed hydrogen bondlength of 0.77 Angstrom. Density functional calculations using commonfunctionals such a LDA and B3LYP differ substantially from the QMC bindingcurve. We show that use of full Hartree-Fock exchange and PBEcorrelationHFX+PBEC obtains close agreement with the QMC results, bothqualitatively and quantitatively. These results both motivate the use anddevelopment of improved functionals and indicate that caution is requiredapplying electronic structure methods to weakly bound systems such as hydrogenstorage materials based on metal ion decorated nanostructures.



Author: Michal Bajdich, Fernando A. Reboredo, P. R. C. Kent

Source: https://arxiv.org/







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