The energetics of oxide surfaces by quantum Monte Carlo

• Published in: Journal of physics. Condensed matter Vol. 18; no. 35; pp. L435 - L440
• Main Authors: Alfè, D, Gillan, M J
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 06.09.2006; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Physics; Surface and interface electron states; Surface states, band structure, electron density of states; Digital simulation; Surface electron state; Magnesium oxides; Density functional method; Generalized gradient approximation; Modelling; Quantum Monte Carlo method; Exchange interactions; Local density approximation
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/18/35/L01

Density functional theory (DFT) is widely used in surface science, but for some properties the predictions depend strongly on the approximation used for exchange-correlation energy. We note recent suggestions that the widely used generalized gradient approximation (GGA) is inferior to the local density approximation (LDA) for the surface formation energy sigma of both transition metals and oxides. We report quantum Monte Carlo calculations of a for the MgO(001) surface which support the accuracy of LDA for this case, and indicate that GGA is too low by ~30%. We point out the potentially important implications of this result for nanoscience modelling.