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Quantum Monte Carlo studies of covalent and metallic clusters: accuracy of density functional approximations

Research output: Contribution to journalJournal article

Published

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Journal publication date1/06/2009
JournalPhysical Review B
Journal number24
Volume79
Number of pages5
Original languageEnglish

Abstract

To assess the accuracy of exchange-correlation approximations within density functional theory (DFT), diffusion quantum Monte Carlo (DMC) and DFT methods are used to calculate the energies of isomers of three covalently bonded carbon and boron clusters (C20, B18, and B20), and three metallic aluminum and copper clusters (Al13, Al55, and Cu13). We find that local and semilocal DFT methods predict the same energy ordering as DMC for the metallic clusters but not for the covalent clusters, implying that the DFT functionals are inadequate in such systems. In addition, we find that DFT fails to describe energy reductions arising from Jahn-Teller distortions.

Bibliographic note

© 2009 The American Physical Society